Purchasing OS X Mavericks for a fresh install
To install OS X Mavericks, the Apple ID that you enter must have Mavericks in the purchase history. If Mavericks is missing, the installer will not let you proceed.

If you had another machine, you could download Mavericks using your Apple ID so that it's registered with your Apple ID. If you even have access to a friend's Mac, you could use that to register the installer.

If that's not an option, you could go to the Apple Store, as was discussed over on ASC:


  I solved the problem by going to the apple store and they reset things for me by installing Snow Leopard on it again. It wasn't until my second visit though so yes they might take a while.