Check this out: http://www.bikeforums.net/showthread...estion-MTB-FAQ.

If you can look around at some shops and try various bikes in your price range, you can get a good feel for what fits and what rides well. The best bike for one person is not the best bike for another, so it's worth trying out a few. You should be able to get yourself a good starter hardtail for that money. Also, any bike can be wheelied if you know how to do it. Short chainstays and high enough bars can make it easier though.