I agree with the posts about your level of want is what will determine your price. I bought a lack mini fridge from CL for 60$. Then I got my keg supplies from homebrewing.org.
Ball lock keg, disconnects, hoses, co2 tank, regulator, perlick faucet, shank, wrench and maybe something's I'm missing... Cost about 300$ then I wanted to build my own top and tower to it.
The keg system kit came with a picnic faucet, so if I only got that and decided to just open the fridge and picnic tap it every time.. I would have spent about 230+ fridge.
But I also wanted to build my own top and tower to mine so that cost me alot more money. It all depends on what you want man.
You can do it cheap just hunt around on Craigslist for as many parts as you can before you buy from online stores.