I'm not saying anyone in their right mind wouldn't want to buy cheapest version, I just don't understand why the public had access to the OEM version to begin with. Building your own PC doesn't qualify you as an OEM, you are still a retail customer of MS if you're not building the PC you're installing the OS on with the purpose of retailing it. The version in PC World was the version the public was supposed to buy whether building a PC or upgrading the OS on an old PC.
It seems pretty much along the lines of 'grey imports' which while not illegal, means you're jumping through hoops to get something you're not really supposed to have.
Anyway, I did say I was going to leave it so I hope this is a bit clearer as I'm going to bed.