The two major purchases (besides beans) are a super quality juicer to grind the nibs into liquor and a wet grinder (sometimes called a melanger) to refine the cacao and sugar. For the juicer, John Nanci of chocolatealchemy.com has tried every manner of appliance, and landed on the Champion Juicer, which is up to the difficult task of turning nibs into liquor without burning out a motor. "I can tell you what won't work", he says, "food processors, a Vitamix, coffee grinders, meat grinders, and mortar and pestle."
For the refiner, the best modern kitchen appliance is a wet grinder that uses a set of granite stones and is used to make some types of Indian food. The Premier Table Top Wet Grinder ($211) is small, powerful, and will make up to 4 pounds of chocolate in a batch. Another option is the Spectra 11 Chocolate Melanger ($479) that will do up to 9 pounds of chocolate at a time or the Cocoatown ECG-12SL that will do up to 10 pounds ($500).
Besides these two devices and some beans, much of the other materials you probably have in your kitchen: Two large (4 quart) glass bowls, some smaller bowls, a firm spatula, a large serving spoon for ladling chocolate into your molds, an old hair drier (all it has to do is blow cool air), a candy thermometer or a non-contact infrared thermometer, and some polycarbonate molds of whatever shape you want. I have found the Fat Daddio's brand of molds, available in most baking supply stores, work great. They cost a little more at 15 to 20 bucks each, but they'll give you smother chocolate surfaces and will last longer than silicone molds.