We can guide you a bit better if we know a little more about what your needs are in a mountain bike. Will it be used strictly on trails, or will you be doing some road riding with it as well? With a $500 budget, your best bang for the buck will be with a used hardtail (front suspension only) which will handle both of those uses. As you probably know, Craigslist is your friend here.
Last edited by rnorris; 08-14-09 at 10:54 PM.