circulating nooks & kindles

The following was posted to the allregions library list:
This question is for libraries circulating nooks & kindles.
How do you prevent patrons from visiting the kindle store or B & N .com and buying e-books that the library then has to pay for?
– We did password protect the nooks, but at least one was returned no longer password protected, and the patron was able to download 4 books!
– We were assured by Amazon that no one would be able to purchase using our acct. without our password. However, I tested this and was easily able to purchase a book directly from the kindle, charged to our library’s gift card, without entering any passwords or the gift card number.
– If we password protect the kindles, then no one can read with them unless we give out the password.
Our borrowing policy, which patrons must read and sign when borrowing an e-reader, clearly states that patrons must pay for books they download. Still, it is much better to prevent this from happening.
Any advice you can provide would be fantastic!
Thank you,
Robin Shtulman
Athol Public Library
568 Main Street
Athol, MA 01331