I'm sorry Michelle but the deal that youare offering is totally against PBS rules. I know you mean well but I don't want to see you get into trouble for this.
Copied from the Help Center:
Can I offer/ask more credits (more than PBS 'price') for a book?
A bound book "costs" 1 credit at PBS (no exceptions)
An audiobook "costs" 2 credits at PBS
- some "children's-length" audiocassette items cost 1 credit each
Offering to "pay" (or asking a requestor to "pay"--see below) more than "PBS price" for a book is not permitted.
- If the book is Wishlisted, offering more than the PBS "price" for the book may allow members to leapfrog over others in the Wish List for the book. This obviously is not fair.
- Even if the book is not Wish Listed, a "free market" system could lead to "bidding" for a book, and auctions are NOT permitted on PBS.
- One reason is that auctions are subject to state laws, and as PBS members belong to various states, this could be illegal.
- The other reason is that we want all members to have a fair chance to get books on PBS. Pitting those who have lots of credits to spare against those who don't have a lot of credits at the time goes against the very spirit of PBS--the fair sharing of books. Everybody equal.
Asking for more than "PBS price" for a book is considered bookselling
- Bookselling is not permitted at PBS
- If you feel that your book is too valuable (or too costly to ship) to be swapped for "PBS price", you should not Post it here.
- If this is a matter of postage cost (your book is heavy), remember that you can also request a "heavy" book with the credit you get for sending yours--so it all evens out.