[darkpuppet]

I would hit up the police auction then -- and bring a friend. You'd likely find something a lot better.

If you're buying used, check the bike for squeaks, make sure the wheels and pedals move smoothly.

If it has a shock, make sure the shock works smoothly, doesn't have scratches all over the slidy bits, and is damped and sprung.

Take the bike in hand, hold the front brake, and roll the bike forwards and back with the front brake held... there should be no clunking from the headset (and no play either).

wiggle the wheels, they shouldn't clunk about the hubs.

spin the wheels, make sure they don't wobble... give the spokes a sqeeze all around the wheels.. they should feel evenly tensioned, no loose spokes or super tight ones.

Make sure the deraileur works and doesn't make excessive noise. They shouldn't be clacking unless you're cross-shifting (big-small or small-big).

that's a start of course....