I too am looking for a North American version of the latest RNS510 firmware and maps. There are a number of good threads on this forum regarding the latest version... and here is a post of the latest DVD that was for sale (but has since been sold) - it at least gives you the info you are looking for.
If you find a copy of the DVD, please let me know. Thanks!
The post is from 05-30-2013, but it looks like Peteski is still active.I just updated my RNS-510 with Firmware Version 4366 and V6M Maps....it made a huge difference. Contact user Peteski on here...he sells both.