While the concept of paying money to get money still boggles my tiny mind, it seems to be something you should take full advantage of right now at ShopTo, as you can get a few extra quid for free when topping up your PSN wallet.
Essentially, the retailer is having a sale on the whole range of PSN wallet top-up cards, so for example, adding £90 to your PSN account will only cost you £78.85. You can then put those funds towards buying games, DLC or PS Plus subscriptions knowing you’ve saved some money.
Using the power of quick maths, it looks like buying the £15 voucher for £12.85 represents the best value for money. Pick up six of them and it will set you back £77.10 instead of the £78.85 you’ll be charged for a single £90 top-up code. Savings upon savings!
Source: Eurogamer Get free PSN credit when topping up your wallet at ShopTo