Where can you buy Capsicum chinense?

Capsicum chinese is a species of hot pepper. The most common pepper in that species is the Habanero. The hottest peppers known, Bhut Jolokia and other similar, are also in the same species. To answer the question, I simply go to the grocery store to buy Habaneros, but I live in the American Southwest and our grocery stores carry that type of thing (otherwise you can get them through mail order).