QUOTE (kas @ 7-17-09, 1:51pm)

One idea for someone on a budget is to look at 'good' bikes that a bike shop might have as trade-ins. I'm willing to bet that some riders don't begin with the top of the line; but will trade up if they have the dough. IMHO, avoid the Craiglist ads, unless a valid receipt can be produced by the seller. Also if you want to avoid the police, avoid the friend of a friend or the flea market vendors.
The used bike market is a good idea if you can find a decent seller. One problem is people tend to overprice used bikes (although not always) so you have to be careful. Ebay is tough because shipping fees can kill the deal, unless you find local. And with ebay or craigslist I often find 2 types of ads:
(1) Here is this thing, I don't know anything about it, I think it's a bike
(2) Here is this vintage completely awesome bike I'm charging 2x what it would have cost new
So you need to know what you're doing to avoid those 2 things. But if you have a friend who knows bikes, they can help.