Craigslist for a used chest freezer, around $50. A couple 2x6's to build a collar, $10. I got my shank, faucet, tank and stuff from beverage factory for just over $100. One keg is fine but 2 is better, scour the web for used kegs for less than $50 each. You can be in business for about $300.
I drink (homebrew), therefore I am (gassy)