It's possible that this is a misprice, but Amazon UK has started offering Gran Turismo 5 for pre-order at the low price of £17.59. If you are in the UK it's worth pre-ordering immediately, although your order may be canceled in the future if it is a misprice. You will be refunded if this happens though.

If you want to pre-order the game, check out the official Amazon listing for the game.