if you hound craigslist in your area for a while, or go to a lot of garage sales, you can eventually find a setup for very cheap...
edit - for example: i got a 20lb co2 tank, dual gauge regulator, faucet, shank, and sanke tap - all for 80, all of my kegs have been about 20 a piece, i got a 50 lb co2 tank for 20 dollars, a 2.5 lb tank for 10, a chest freezer for 15, 6.5 gallon carboy for 15, 5 gallon carboy for 5. that's all i can think of right now. but craigslist and garage sales are definitely your friend.
edit - for example: i got a 20lb co2 tank, dual gauge regulator, faucet, shank, and sanke tap - all for 80, all of my kegs have been about 20 a piece, i got a 50 lb co2 tank for 20 dollars, a 2.5 lb tank for 10, a chest freezer for 15, 6.5 gallon carboy for 15, 5 gallon carboy for 5. that's all i can think of right now. but craigslist and garage sales are definitely your friend.