Yeah you can work it out with who ever you're buying, selling, or trading to.
You can send cash in the mail if you put it in a birthday card or something.
CRUCIAL: If you don't include in the thread that you're selling in that you can't deal through PayPal it can result in negative rep, karma, and feedback. (It might even end up as a temp ban)
There are other more complicated ways as well. (Listed Below)
Google Checkout (parents permission required)
PayPal (parent permission required)
Moneybookers (I'm not sure about this one)
(I'll extend the list if I come across more)
[Skullcandy] [Click] [Scott poles] [Head skis] [Electric Eyewear----DROPPED] [The-House]