Be absolutely certain to get insurance and ALSO signature confirmation so they have to sign for the package. I would also be hesitant to ship overseas since this is a one time deal where you don't want any headaches.
I would also recommend doing the opposite of keeping the funds in your paypal account. I would withdraw the funds to your bank account, and ONLY ship the ball once the funds are confirmed to be in your bank account.
Others may chime in, but I'm pretty sure those are two pieces of good advice.
