I blogged a while back about roasting at home. I mentioned what you need to gather - unroasted coffee, a decent popcorn popper with sufficient wattage (1200+), and a ventilated area away from anything you wouldn't want to burn down.. Now this is not quite the same level of danger that frying a holiday turkey seems to be, but things do get hot and burns hurt. If this warning has not scared you away then keep reading. If your palms are sweaty then keep buying the good stuff roasted by the pro's.
Just a quick note about this piece while we are on the subject. Most people I know who roast coffee at home also continue buying roasted coffee. Doing one does not mean you can't do the other too. I think of it as a hobby and I use what I get and really enjoy from an artesian roaster as a template for my own amateur efforts. If I get close I am ecstatic but if it just tastes good I am happy. Roasting a quarter pound of greens is not hard. In fact it is very easy. The hard part is trying to get consistent batches from the same beans using a cheap popper. Considering that a used popper will cost about $4 bucks and a new one will cost around $20, some variability in the roast is acceptable and should be expected.
This variability might put you out of business if you are trying to make a living turning green beans into dark brown ones, but for a home roaster this variability adds to the excitement as far as I am concerned. A large commercial roaster can bang out batch after batch using the same time and temp profile and the same beans will pretty much taste the same through out the lot. Home roasting can be like trying a new coffee every time. Didn't like the way this batch tastes? Roast another and depending on line voltage quality (which is subject to a surprising amount of variability throughout the day) and ambient temps the new batch can taste very different even using the same beans.
Still this is an excellent way to learn what to smell, look, and listen for during the roasting process. It also lets you find out on the cheap if the hobby is even something you want to continue pursuing. Either way though it will give you a better appreciation for the people who roast on a professional level.