I got the Gamestop pre-order Anniversary edition. It came with an extra 20 special Anniversary edition cars.
All anniversary editions come with 5 special cars.
The Amazon pre-order gave you 1 million credits to start with.
The regular edition doesn't come with anything I think. Try calling gamestop and pre-ordering still. They probably have copies left. The 25 cars are bad ass.
http://www.gran-turismo.com/us/products/gt6/preorder/#anniversaryI paid $5 for the pre-order and $60 for the game... so $65 total. The Anniversary edition isn't more expensive.
If you can't get the gamestop edition, I can hook you up dave. I saw that I can use my code on my one other connected ps3 (yours).

You might wanna just get the Amazon one with the million credits then use my code to get the 25 special edition cars.