Hot Air Popper
The cheapest and simplest is to use a (cheap) electric hot air popper. The old favorite is the West Bend Poppery, but you can use anything as long as the vent holes (where the hot air comes in) are on the sides rather than the bottom.
I've roasted a lot of coffee this way. It works, but there are a few downsides. The biggest problems:
- The circuation is designed for popcorn, which expands a lot more than roasted coffee beans. I've needed to stir the beans manually in order to get an even roast. They don't have to be stirred constantly, but you can't just drop the beans in and walk away.
- The capacity is pretty low, especially when you take the circulation into account. I can only roast a half a cup at a time, which is pretty slow.
- The temperature doesn't get quite high enough to really bring the flavors out. The roast is good, but it's really mellow.
![alt text](https://farm5.static.flickr.com/4067/4698574374_4fe844082d.jpg)
[source: Chris g Collision, Flickr Creative Commons]
I've read about modifications you can make that will improve these: changing out resistors, modifying the airflow, and even hooking up an Arduino to control the heat a lot more closely, but it seems like more work than I've wanted to invest in the process.
Heat gun / metal dog bowl method
My brother's moved on to this approach, and I'm soon to follow. The benefit of a heat gun is that the temperature is high enough to get a good roast, and the airflow is high enough that you can roast a few cups of coffee at a time.
![alt text](https://farm3.static.flickr.com/2722/4381304990_9cca36e5b1.jpg)
[source: Ocell, Flickr Creative Commons]
More Insanity
Sweet Maria's sells green coffee beans, and lists a huge amount of home roasting methods, including Weber Kettle conversions. The sky's the limit, but I'd start small with the air popper or the heat gun first.
I'd do this outside
Some methods have you roasting the coffee in your kitchen - in the oven, on the stove, etc. I wouldn't want to do this myself, for two reasons. The beans have thin husks on them, which come off as the beans are roasted. They're messy, and I wouldn't want them flying around my kitchen. Also, roasting coffee doesn't smell as good as you'd think it would.
Sources of more info:
To answer the second part of your question ('the pros and cons of an espressomachine'):
Pros:
- Taste. If done right, you will capture much more of the coffeebean in your cup.
- Milk foaming. Most espresso machines have the possibility to froth milk for cappuccinos or lattes. Look up 'latte art' on Google Images for some inspiration :-)
- Process. The making of coffee becomes an enjoyable ritual with shiny machines, hot water and steam.
- hobby: there is an enormous amount of ustensils, tools, cups, coffees, online forums etc. to discover for enhancing your espresso.
Cons:
- Taste! as much more taste ends up in your espresso cup, you will also taste the defects much better (bad or stale coffee, badly grind, wrong water temperature etc.) will give you a sour or bitter cup.
- Technique. It takes practice to prepare a good espresso (except if you opt for a machine that takes coffee pads - but your choice of coffees will be limited and often not fresh).
- Cost. Espresso machines (good ones) are costly. And it doesn't stop there. To make really tasty espresso you might want to grind the beans yourself, so you'll need a grinder that can grind fine enough for espresso. After that you might start to suffer from upgraditis...
- Room on the kitchencounter. An espresso machine can take up quite some space.
Hope this helps!
Best Answer
The manufacturers will tell you:
A similar reason goes for vinegar. And Citric acid (from what I'm told) is less problematic than vinegar.
The real expensive stuff like Durgol isn't actually citric acid and some other formula (unlike citric acid it tastes awful).
Here is their description (pdf)
While your machine's specific kit might be dosed for perfection, you're likely ok with any descaler for the size of the machine. A competition grade professional machine on the other hand, I'd recommend vicious service. If you only see what's under the shower screen of some of the machines out there in the wild.
A key point is that they claim their product is faster. So if you have time, and are willing to rinse a quite a few more times, I wouldn't worry too much about it.
The Cafiza powder from Urnex is really good at cleaning coffee grime, but does not de-scale/de-calcify. I would recommend it for cleaning coffee urns and the coffee stained parts of your machine.
Finally, you might wish to use softened water. It'll make the coffee taste better and reduce the build up.