I've been on the receiving end of a bunch of bad negotiations in RPGs. Real life negotiation training helps, but there's also some RPG specific aspects to keep in mind.
Often, the problem is that there's some adventure hook that requires the PCs to do something that's totally stupid. "Hi, you're level 10, would you like to go on a fetch quest for 100 gp?" Or the classic module Against the Giants, where the locals decide your high level party is guilty of unspecified crimes (vagrancy?) and must go kill 100 giants to atone. Even LG parties respond to that with "You're going to look mighty funny with that longsword sticking out of your ass." Your non-derogatory use of the term "railroad" (generally considered bad) leads me to believe this may be the case - if you expect the PCs to "take the adventure hook" you present them regardless of its desirability and they are trying to live in character and not go for some awful deal their characters at their current wealth and power level would never contemplate, you'll be disappointed.
Now assuming there's at least the makings of a deal, meaning each side has something the other person reasonably wants and might indeed exchange (goods, services, money, etc.) you need to remember that people want to make deals and that they can be win-win.
Allow me to use the framework presented in Getting to Yes, a book on negotiation everyone should read.
Separate the people from the problem. Put yourself in the PCs' shoes. Listen more than you talk. Get them involved. Help them save face at giving in on things. They should ideally be doing the same to the NPC.
Focus on interests behind positions. Ask "Why" and "Why not?" Be hard on the problem, soft on the people. How can everyone's goals be achieved? Don't attack the other person's position, look behind it. When they attack your ideas, ask for advice. Ask questions and pause. "How can we make this deal happen?"
Invent options for mutual gain. Generate a range of options, Use imaginative procedures. What other things does someone have that they'd be willing to do or give away that the other person might value more? It doesn't have to be a flea market "Five dollars! One! Four! Two! Three! Deal!". That's a one-dimensional negotiation. Timing, loot, favors, future goods are all possible. "What else can I throw in?"
Use independent standards. What is this really worth? If someone's being unreasonable, you can show what the item or job is "worth" to others. "These guys will do it for half the rate, but I want you to have the first crack at the loot..."
Develop a best alternative to a negotiated agreement. If one side has to have the deal or they're completely screwed, they are in a bad position. As a result most people have a plan B. As a DM, you need one too, besides "tell them out of character to take the bait." Maybe it's some kind of setup or extortion (e.g. the PCs' rooms get ransacked and a convenient clue is left behind pointing at the people the adventure hook is trying to sic them on. Of course the other negotiating party did it, but PCs are usually dumb and easily pointed in a direction.)
Of course, you can just let events transpire. In your example, the PCs got suspicious of the sage. So? Can they not get the information any other way? Are there no other people they can go to? Do they not plan to just stage a home invasion and interrogate him (normal PC response to something like this)? Your problem is less about negotiation and more about poor adventure design and railroading. Should there really only be one way to proceed in the plot? It's best if not; but if it is then the PCs will eventually have to give in or beat it out of him... I find you always get the best results from handling things in game, not with metagaming and railroading. It may seem expedient now but it's a long term poison for your game.
Don't run a World X game. Run an alternate universe World X game.
Sure, your players are expecting a World X game. But you don't know enough details to run one. An alternate universe game lets the players enjoy the genre they want while you still retain control of the details.
Three basic steps:
- Introduce some elements that are definitely wrong.
- When they notice a discrepancy, make it seem intentional.
- Make up information for the characters to know, and give it to the players.
Let's say you're running a game set in 1920s California. You might know some things about the 1920s, and you might know some things about California, but let's assume you have some players who know far more than you do.
Introduce some elements that are definitely wrong.
At the very start of the game, throw something in that makes it absolutely clear that this isn't exactly the 1920s California they're expecting.
DM: We begin the game in San Francisco, June 3rd, 1921. It's a cool morning here in Union Square. Men in tweed jackets are headed off to work, lunch pails in hand. Fruit sellers are opening up their stalls. A young boy is standing on the corner, selling copies of the Chronicle. The headline catches your eye -- "Kaiser Accepts British Surrender".
With a single headline, they know this isn't the world they were expecting. But if the game is set in California, events going on in Europe are just background. It doesn't really matter what's happening in Britain at the time, but it does set the scene. This is not our 1920s.
Let the party find out, in passing, that Abraham Lincoln was assassinated in 1860, just before the presidential election. Russia's been communist since the 1890s. No one's ever heard of a banana.
It is the right setting, but you've established that the world does deviate from their expectations in little ways.
When they notice a discrepancy, make it seem intentional.
Let's say they're talking to the mayor of San Francisco, James Rolph, and they call him by his nickname "Sunny Jim". The players know that this was a nickname he liked, but you don't know that, so you have him take offense to it.
Frank: I go over to the mayor and strike up a conversation. "Good morning, Sunny Jim, how's it going today in this fine city?"
DM: {as mayor} "Excuse me? How dare you call me 'Sunny Jim' like I'm some pal of yours?" The mayor looks very upset.
Frank: Wait a minute, everyone knows he really liked being called "Sunny Jim"!
DM: Kinda makes you wonder why he doesn't like it now, doesn't it?
Now the party's trying to figure out what kind of man the mayor really is, and why he's so harsh to deal with. Maybe there's some secret here. Maybe he's just an angry sort of guy. But you've already established that this world isn't quite the one they know from the history books.
Make up information for the characters to know, and give it to the players.
If you're going to do an adventure out in the farming towns of the central valley, and one of the characters is from there, give them a map you made up yourself. You can do a bit of research to get the basics, but it's ok to make up towns or leave places out. The players already know that the world isn't quite like ours. And when you give this map to one of the players, representing their character's knowledge, now they get to be the one presenting it to the party. The fictional facts become their facts, not just your facts that the players are disagreeing with.
This way, the players know the genre, but not the story.
Most of their general knowledge will be correct. Laser pistols don't exist. Telephones do, but they're not too common. Newspapers carry stories from across the globe. Africa is dark and mysterious. San Jose is a quiet farming town. But their specific knowledge doesn't give them any spoilers. They won't be able to predict the 1929 stock market crash, because they know that this isn't exactly the world they've read about. They can't use Wikipedia to learn things their characters wouldn't know.
Best Answer
"You've just moved into town and you wanna know the big players. Fair. There's the basic info you're going to get from your usual methods - you're shadowrunners, this is part of the job. BUT - tell me a) how long do you want to spend researching, b) how low of a profile do you want to keep in this, c) how much are you willing to spend? Detailed, fast, quiet, cheap - pick 2."
The trick to good info management isn't withholding information from the players, it's about figuring out what methods and prices they have to pay along the way to get what they want and building the adventure from that.
Are they doing things discreetly? Or are they leaving trails? Will some groups tag them as trouble makers, potential rivals, or good suckers to throw in on a bad job?
Are they pissing people off along the way? Making enemies in a town where they've got few allies?
Are they throwing around a lot of money? Are small time runners looking to jack them? Are big time players suspecting they're just a front for a rival corporation/group?
Are they asking "too many" questions about a particular group and word is getting back?
It's not just the price you pay in time and effort, it's also what the rest of the world thinks of that, and the actions everyone takes in response.
Mechanically - it's as easy as a dice roll. Fictionally, as a Shadowrunner, you're stepping into someone else's mess and maybe you want to step carefully.
As far as playing it out and not writing massive setting stuff, ask the players in return - "What are you looking for? Are you looking for employers? Marks to hack/rob?" and target your answers around that. For some details, on a successful roll, you can turn the question back on them - "Well, 'Uncle Knife' still runs the docks, which is damn impressive in day and age, but he did something that has caused all of his rivals to back off - you only figured it out when you looked at a shipment record from something 2 weeks ago. What was it?"