I'm not sure of the differences between the mail away version and the retail versions either. Honestly I didn't know there even was a "mail away" version. I know there was a pack in version that came with the turbo duo and there was also a retail version. The retail version came in the box with hang tab and the pack in came with either a normal turbografx case or a cd slip. Either way I can tell you that I saw a retail version sell on eBay by Buy it Now for $125 about a week ago. It sat up for a few days and I sent a message to the guy, he said he would take $100.