heavily photograph the print, corners, edges, number, etc.
Get paid via Paypal.
Ship via USPS Priority, in a yazoo mills tube, with kraft and tissue paper, with the roll taped smalled than the tube.
For a 1000 dollar plus piece, I'd generally ship the tube inside of some sort of shipping box, (with padding/bubble wrap around the tube) for an extra layer of protection.
Insure for the full value.
Make the buyer pay for shipping + insurance.
More like get paid with a bank wire. You don't want them doing a credit card chargeback or some other kind of dispute. Ebay/paypal fucks sellers too easily.