A new service has been added with prime subscription and Makes prime worth it. I didn't need a VPN to access it on a trial subscription so YMMV
This service includes (streaming only):
Unlimited access to Audible Channels, a collection of short-form audio series that include podcasts by CNET and the Onion, as well as original programs.
Access to a rotating selection of Prime Exclusive Audiobooks that include a collection of best sellers, family favorites, celebrity-narrated classics, and more (available for Prime members to stream at no additional cost).
I think you just need a US address in your amazon addressbook to get prime.