Howdy, Can't say much
but If you want resnable dragonball cels and 
don't really care who's in them..
http://www.anime-cel.com/dragon.htm
Is VERY resnable..It might be good for your 
little brother to start with and wouldn't be much 
out of the pocket book for starting out..

otherwise..Good luck on finding DBZ cels under 100
$ on main characters..Heh I don't see that happen 
to often..It's rare but I have seen dealers here 
post them for such you just have to watch:)