Don't go above 50 bucks: that rear wheel is going to be expensive, unless you just re-dish it yourself and use loc-tite, which honestly just seems like a PIA. My only words to you: go with a bike with all steel components. Also, don't try and convert an old Raleigh three-speed frame. Try and get something with cotterless cranks (see sheldon brown for info) and alloy/non-steel components. Otherwise, it'll all be heavy, and you'll end up wanting to buy better components anyway, and that'll all run you up!