There's no cart or any of that. I'm just an old-timey pencil-pusher, so send me a list of the books, art or whatever you want to buy and I'll figure up the shipping and send you a Paypal invoice. Easy peasy!
If you need something drawn to order, I'll work with you, whip up a preliminary sketch if you want and get a good idea of whatever you've got in mind. I do require payment in full before starting work on the actual piece.