What is the main kind of riding that you'll be doing? Commuting, recreational rides? City streets, paved or gravel paths?

If the bike is in good shape (no dents on the frame, no rusting, shifts properly, tires are in good shape and not cracked, wheels spin straight and don't wobble), then the price sounds fair, but you want to make sure that the bike suits what you'll want to be doing, and most of all...that you enjoy riding it!