My advice is to spend at least 350-400 bucks, whether the bike is used or brand new.
I got a new Giant Yukon for around $400 when I started at ISU in 2004. I used it for biking around campus and some singletrack riding through 2009 when the SR Suntour (not a great brand of fork but typical for entry level mountain bikes) finally blew out. I replaced it with a $200 Marzocchi fork from Bike World, put on a new chain, and rear cassette and used it on a spring break MTB trip to Colorado and Utah. It got me through a team 24 hr mountain bike race in Boone and lots of rocky singletrack riding around KC over the last 2 years. Finally this spring, I decided to upgrade to a full-suspension Giant Trance X2 because my riding style had outgrown that bike. It is still perfectly ridable for beginners or on less rocky terrain.
Moral of the story, any $100-200 Wal-mart bike would not have survived the abuse I put that bike through. Spend a little extra and you will get a lot more.
I got a new Giant Yukon for around $400 when I started at ISU in 2004. I used it for biking around campus and some singletrack riding through 2009 when the SR Suntour (not a great brand of fork but typical for entry level mountain bikes) finally blew out. I replaced it with a $200 Marzocchi fork from Bike World, put on a new chain, and rear cassette and used it on a spring break MTB trip to Colorado and Utah. It got me through a team 24 hr mountain bike race in Boone and lots of rocky singletrack riding around KC over the last 2 years. Finally this spring, I decided to upgrade to a full-suspension Giant Trance X2 because my riding style had outgrown that bike. It is still perfectly ridable for beginners or on less rocky terrain.
Moral of the story, any $100-200 Wal-mart bike would not have survived the abuse I put that bike through. Spend a little extra and you will get a lot more.