Thanks everyone for their input. Yauncin--I will probably look into options 1 or 2, as they seem to be the easiest (and cheapest) to do; I know they are not as accurate as the others.
01gt4.6--that's how i figured things, too. I would much rather have the 180 weight be muscle of course. But when people start working out, how much increased muscle mass do you see? 5 pounds? 10-20?