CAD programs?

well my whole family wants some kind of cad, we can pend money on it, and was looking at a new frys electronics today and saw good deals and all that and we didnt buy anything because we dont know which to get.... what can i use for all rc stuff? under a 100 bucks probably, i want to do all the cool stuff, idk if rendering will be in there or not, but something 3d, idk any recomendations? whole family wants it, 5 ppl, so we dont need a cheap learing kinda thing or sumthing if there is because one of us will keep on doing it lol

sorry for the babling, im done now:018: