http://www.cdkeys.com/playstation-network-psn/psn-cards
CDKeys , no longer quite as good of a discount but still worth using
With the 5% discount for liking them on facebook you'll get :
£15 for £13.29 so your paying 88.60p for every one pound
£20 for £18.05 so your paying 90.25p for every one pound
£25 for £23.32 so your paying 93.28p for every one pound
£30 for £26.59 so your paying 88.63p for every one pound
£35 for £31.25 so your paying 89.28p for every one pound
£40 for £35.14 so your paying 87.85p for every one pound
£45 for £39.89 so your paying 88.64p for every one pound
£50 for £43.69 so your paying 87.38p for every one pound
Best deal is the £50 but if you want a smaller amount there are slight savings by avoiding the £20 and £25 cards