Welcome to the forum! I'm a newbie to MB's myself. In the $100 range your looking at a Walmart bike or something used. This seems to be one of the few hotbutton topics around here. Check out this thread, http://motorbicycling.com/f3/debunki...kes-30242.html
Plenty of opinions there, you don't want to start that debate again here, that's for sure. Again, welcome to the forum!