Was looking around for the best price to buy Little Big Planet 3 on PS4, most places still well over £40. On the Play.com front page they are advertising a £10 off £40 voucher if you purchase through Rakuten. Found the game via The Game Collection seller for £39.95 (others over £50!) cheapest item I could find to take it over £40 was a pre-owned blu-ray at £1.95, making the total £41.90. Use the GIFT40 voucher and makes it £31.90!
Obviously this would work on other games too but a great price for this game which will be a hit over Christmas!