Using PayPal F&F on the Boards is not allowed. It also leaves the buyer no recourse in case something goes wrong. See #9 on the Usage Guidelines:
While on the subject of Board Rules, there is no Board Rule that stipulates in a thread trumps PM negotiations, that's merely a rule several sellers stipulate that many people copy. When I run a sales thread, it doesn't matter to me if someone wants to remain private and buy a book via PM or not. As long as I have an unqualified, definite "take it," the book goes to that person.
Finally, I thought you were going to wait until you had the boxes in stock? I'd never put books up for sale unless I was able to ship them.