Cervelo P2C 2007

It depends on a few different things... first, does the bike even fit you? Bike fit is HIGHLY individual and height is a poor indicator of fit. I'm 5'9" and a 56cm P2C would not fit me (then again, Cervelo's just don't fit me well in general...).

Let's say that it does fit. If the bike is well maintained (chain is not worn, cassette and chain rings in good shape, cables and cable housing newer, brake pads not worn out (or dried out since it's a few years old by now), tires not worn out, wheels are still in good shape (bearings and brake surface). frame has no deep scratches or cracks, etc.) then $700 is a very good price, you are getting a very competitive bike for that amount of money, and you can't do better with a new bike for the same price. If the frame is in good shape, but you need to replace cassette, chain, chain rings, cable/housing, expect to spend about $250 if you do the work yourself (requires tooling and knowledge) and add another $150 if you have your LBS do it for you. Tires add another $100, wheels add another $75 if they can be rebuilt and only require bearing, $150-200 if you need spokes and hubs or $300+ if you need new wheels.

Basically, as long as everything is maintained really well and it fits, it's a good deal. If it's not maintained well, then the cost can escalate quickly and it's maybe not such a good deal... If the bike doesn't fit, then it's a waste of money.