In general, there's so much value with used bikes. If you can find the style and fit you want, you'll likely pay half or less compared to what the first guy paid. The '97 Trek 850 mountain bike I picked up for my daughter about a month ago was in the local CL's "Free" section. Seriously. I called the guy 4 hours after he posted it, just knowing it was gone. He still had it. It needed two tires (the original Big Kahunas were rotted, unfortunately) and two tubes. I've changed some parts around among a few of my bikes, and she's got a nice set of EF51 shifters on it and a set of Avid Single Digit 5 brakes, and the thing rides like a new bike. It's 20 years old! Free! Just needed some tires/tubes/TLC (the other parts I put on were of my choosing; it didn't NEED them).

Best of luck in your search!