Looking through my local C-list ads produced this:

http://orangecounty.craigslist.org/bik/3188447830.html



$149.00 for a Gary Fisher Hoo Koo E Koo. Looks like it'll need tires. Old mountain bikes make great all around bikes when street tires are installed. This is just an example. Figure out what you really want to do with your bike, set a budget, gather info.