Only you can answer that. If you have the money to spend, go ahead.
bike
Snowboard because its better than a dirt bike.
Depends on how much they owe on the bike and if the price of the bike includes pay off to their bank and you get the title. If there is a lean holder on the bike and after you buy it you don't get a title then no I would not buy the bike.
pleasure
The bike that you should buy for your nine year old son is that with a 20-inch wheel with suspension forks and adequate front suspension.
The best bike to buy for a nine year old active boy is a 24in-wheel bike with a 3-speed hub gear.
U can buy one on Craigslist (used)
DiomandBack Groove
buy a big and nice bike
they are more stunt bikes but if you want to do more jumping on and of you should buy a trial bike
You can get a stationary bike at any of these following places I have found for you to have a look at. Wal-Mart should have some, best buy, Lowe's and sears has a few. I hope these places help you as you look for a stationary bike.
I don't think you need a licence to ride any sort of bike you should just buy a bike and ride it its not like cars where you need licence's because with bikes you can just buy it, ride it as there is no place at all to buy real bike licences. If somebody has told you you need a licence to ride a three wheeled bike you shouldn't have to for ANY bike.