C.M.
All you need are a few 2x4's and some soil. I have an EXCELLENT garden for the first time because of square foot gardening.
This is a website to look at:
http://www.squarefootgardening.com/
Seriously. I have eaten the best spinach, broccoli and lettuce so far and am waiting for my squash and peppers to come in. It is pretty inexpensive to start and easy to keep up. Good Luck!