Assuming you want a mtn bike, there should be wide range of decent bikes available in your price range. Trek, Giant, Cannondale, and Schwinn all make decent bikes at this price. You should be able to get a good mid-level front shock, along with decent Shimano componentry (acera, st, stx). Stick with a hardtail and stay away from full suspension bikes at this price point. The full suspension bikes may seem tempting, but you really have to spend twice as much as what you're looking at to get a decent one. You'll get much better value for your money if you stick with a hardtail. Pilotpip's advice is golden....fit is very important. Don't waste your time with a shop that doesn't take the time to explain how the bike should fit as well as find the right frame size for you. Also, REI has great selection and generally knowledgable salse people, but shop around for price once you decide on a bike. Big stores like REI often won't give you the most competitive price. Plus its always nice to support your local mom and pop shop.