If you are 12, and are asking about how and where you can make money with one trick, you are NOT ready.
At least if you want to get paid, get a little routine. Ex. STS into TDW, into stealth pen, into dollar bill vanish with TT and keep their dollar bill. Just think of your own and practice your crowd control, patter, mechanics, ect for people around where you live for free. I would wait till you are 14, 15, 16 at the earliest and work as a restaurant magician that gets paid every day a good amount.
As for what you posted, it does not sound like you are ready (unless you were doing magic at 6 months old...) So, hone your skills, practice, and get a ROUTINE down.
Hope this helps,
Don't 'keep' their dollar bill! If you earn it, you will get it. But by keeping it, you will leave a bad taste in their mouth (even if they don't admit it).
Also, try working with some sleight of hand. It's much easier to put routines together using sleights than by buying gimmicks like RAngel has suggested.
As someone mentioned, you'll have a better chance of making money by mowing lawns and walking dogs than doing magic at your age. But don't let that discourage you. If you practice and take it seriously, by the time you are 16-17, you'll be more than ready to get a magic job.