Unless Warcraft changed something, mundane crafting does not cost XP
Mundane crafting requires Craft skill checks, but no Item Creation feats, and the costs are only time and money, not XP. Specifically, they cost a mere ⅓ of the base price of the item, but crafting takes a number of weeks equal to
(P×10)/(DC×check)
where P is the item's usual price in gold pieces, DC is the Craft DC, and check is the crafter's Craft check result. This formula results in phenomenally long times, but at ⅓ the cost there is a lot of savings.
Magic items require XP, but that is easily replaced
In many places, XP costs are replaced with gp costs or vice versa at a 1:5 ratio. Since magic items cost 50% the base cost in raw materials and 4% the base cost in XP, you can apply the same conversion: five times the 4% is 20%, which can be added on to the existing raw material cost to get 70%.
Thus if magic items simply cost 70% of the base price to craft, instead of 50%, but don't require XP, this is consistent with the original system. Taking an Item Creation feat only enables a 30% discount but doesn't leave you behind.
I have played in quite a few games that make this change; it didn't dramatically improve the popularity of Item Creation feats for players, but it does make them much less of a headache for the DM.
If playing with Eberron Campaign Setting (the book, regardless of whether you play in Eberron) in play, the artificer and Artisan feats do require a little more tracking: it is important to remember that 50% of the base price is the original raw material gp cost, while 20% is the "XP" cost. The artificer's Craft Reserve and Retain Essence class features, as well as the Artisan feats, should be applied before adding these together as the 70%. The Craft Reserve should also be multiplied by 5 gp/XP for consistency.
If either is too expensive, these items were not intended for characters of their level
These processes both result in significant discounts. The value of items is used to control the power of items that players have at a particular level, which is part of the system used to try to ensure that enemies the same level as the players are challenging without being impossible. Making items cheaper or giving players more gold may allow them to steamroll opponents; making items more expensive or giving players less gold, or giving them gold but no place to spend it, may leave players without the tools they need to contribute.
In my experience, there are many classes that just barely find the default wealth rules sufficient for their needs – if they spend carefully. Other, more powerful classes are not nearly so needy, and could do with less. As a result, reducing wealth is something I strongly recommend against – it disproportionately hurts the classes that were already weakest.
On the other hand, I tend to find the system has a fair amount of room for extra wealth before players really start to steamroll. Thus, your choice to make it easier to get items is a move in the better direction.
But do be careful; wealth expectations are a rather fundamental design assumption of the game. Great care should be taken when modifying it. I tend to recommend that new DMs stock fairly close to the guidelines. It takes experienced DMsa lot of care to get modifications to wealth to work the way they want.
The rules are ambiguous, but I think they lean to "yes."
As you know, it's not explicitly spelled out in the DMG. But I think they lean your way, and here's why:
- On p.128 "Crafting a Magic Item" lays out the prerequisites for a character to craft a magic item: (a) a formula for the construction; (b) a spellcaster with spell slots--Magic Initiates need not apply--and knowledge of any required spell; (c) character level minimum.
- Later, near the end of that section, we find a few paragraphs dealing with ancillary matters: lifestyle while crafting, custom items, and assistance. The paragraph on assistance calls out the character-level prerequisite for any assistants, but doesn't mention the other two. The designers could easily have said "if each of them meets the requirements to create the item," but instead mentions only requirement (c) from above. Admittedly, an argument from omission is pretty thin.
Unfortunately, there's a decent counter-argument of nearly the same strength: "anyone who assists is a co-creater, and thereby must meet all the creator's requirements. The level requirement is simply called out to make it clear that another spellcaster with the right spell but not of the right level could not assist." Of course, this line of reasoning would moot "if each of them meets the level prerequisite," which I find intolerable.
But it doesn't matter, because it's explicitly your call. (Of course, all things are ultimately your call, but this one's called out as such in the DMG.)
Back it up to the very beginning of "Crafting a Magic Item":
As an option, you can allow player characters to craft magic items. (loc. cit., emphasis mine)
Obviously we all understand the "golden rule" of GM-ery: Make decisions and adjudications that enhance the fun of the adventure when possible. (Repeated at the start of all of Wizards' published adventures, and a good paraphrasing of "The Dungeon Master" from the introduction to the DMG.)
But I'd suggest a broader understanding of published materials: what we purchase in the core set is not (just) a game. It's a system, with a game as a worked example included. The rules presented provide you with a default game playable out of the box, but also everything you need to construct a game after that fashion. Every rule, in my opinion, is preceded by a silent "and here's one way to do ___:"
Best Answer
I think there's two reasons why it would make sense for magic item creation costs to be as high or higher than purchase cost, that fit with the idea of D&D and the stories portrayed:
Most of the permanent stuff for sale is ancient
For most of it, it doesn't matter how much gp a caster once spent for it. The magic item for sale in the Bazaar of the Bizarre isn't made by the owner, or anyone he knows. It's made by an ancient wizard, who died centuries ago, and isn't going to see a penny of that money. It was probably looted by adventurers, who then decided they didn't need it all that much, so they sold it for whatever they could get for it and now it's for sale for whatever the item's owner thinks he can get for it.
The reason he asks you for 2000gp, even though you can make it for 2000gp is because A) most of the people who can afford a magic item, could also make one themselves and B) he's now undercutting any bored Wizard who tries to compete with freshly made magic gear. Considering these magic items are practically indestructible and require next to no maintenance, there's eons of time that they've been made in and most are simply still around to be found.
The market for permanent magic items is terrible because the stuff literally lasts forever and there's a whole class of people whose only job is to venture into the wilds, "liberate" the items and then sell them cheap so they can get some more potions for their next "adventure". Sellers are simply responding to this dynamic.
Most of the consumable stuff is made by specialists
The reason your Wizard takes 4 days to write a scroll and spends a 100gp on it is, for a major part, because your Wizard is a firebreathing, lightning throwing, people charming, monster summoning murder-machine and not a scribe.
Probably if you decided to spend 90% of your time learning how to write a Scroll of Burning Hands faster and cheaper than usual, you could also learn to do it in half the time and for half the cost and earn some money selling those scrolls to the other Wizards who don't perfect the art of calligraphy but instead waste their time going out to kill things and take their stuff.
You simply cannot reasonably compete with the people who dedicate their lives to creating consumable magic items and never learn to survive adventures. (And the reason there aren't any rules for doing so is because this is Dungeons & Dragons and any such character would be an NPC, not a player character)
Why you can't make money selling magic items
Ultimately, what it comes down to is this: making a lot of money off of creating and selling magic is boring and not what D&D is about, so the standard rules don't allow for it. The above is just flavoring for why it's like this.
Any experienced DM who can turn "making and selling +1 swords" into a fun play session will have enough experience to tweak (or disregard) the rules so that it works.
Any DM who doesn´t have that level of experience cannot accidentally screw up his game by showing his players how to make loads of money without actually risking their hides in the adventures that the game is about.
It's a win for everyone.