basically, you want an ALL cromo frame when looking. Everything else can be upgraded as they wear out/break. You can move all the parts over if/when you decide to upgrade the frame, so long as the BB and Headset are the same. I'd spend a little extra on a complete with a full cromo frame instead of a bike with anything Hi-tensile tubes on the frame in your price range. Good choice on going the bmx route, the parts and bike will usually last a lot longer than other bikes in the price range. You'll have more fun breaking *ahem* wearing them out than on a hybrid or other bike.