I am looking for a BMX style bike (handle bars and frame that means that it has a low lying seat) but would like a mountain bike style gear mechanism and mountain bike style wheels. A must is Disc brakes. I am unsure of what makes or where to look for this type of bike. my max amount is around £400.
any advice will be gratefully accepted
P.S. how hard is it to replace V style brakes with Disc brakes