A razor or nair is the cheapest way; but nair smells weird. Depends on what regions you're wanting to remove hair at, I guess. Waxing is the best and the results last longer but you'll have to shell out some $$ for that.
not sure exactly, but my guess would be anywhere from 40-80 dollars. If you get it all done at once it'll be cheaper. Call your local salon and they can give you more specifics and prices. Good luck.
Razor's the best way. Removal creams can leave nasty ingrown hair if he's got coarse hair. Also be carefull which way you shave in different areas. Against the grain can be an issue in areas that rub together, (inside elbows, etc).