If your budget really is $100 and that's it, then RC flying isn't for you. This is a hobby that does cost money to do, and you will incur expenses as you go. You might consider control line flying since that doesn't require a radio and the small engines don't cost much. I hope you understand, I don't want to chase anybody out of the hobby because I think it's great, but there are people all around who got into the hobby and spent what money they had on it only to find out they really couldn't afford it and wind up with nothing. A better route is to save your pennies until you can afford a quality plane (the aforementioned Super Cub is decent) and can join a club that has instruction. Allow some money for incidentals so that a small setback like a wreck or a battery going bad won't put you out of the hobby. Then you'll be successful and really enjoy the hobby like you want to.