I have sent in two $20.00 bills to the Ron Paul campaign. Each time they sent me free bumper stickers.
Is it legal for teenagers to contribute to political campaigns?
It is. I donated $20 to Bob Casey when I was 16 to irritate Keystone Phil.
I've seen fairly young kids (5-10) give a dollar or two to political campaigns at events, and fill out the disclosure paperwork. As long as the kid wants to, it's legal.
You were willing to spend money just to irritate some random person on the internet? That's dedication right there.