These cards are normally difficult to find with a discount and £9.85 is about as cheap as it gets when they come up on a deal. I use these for my DSi, enjoy. (it says Usually despatched within a month but last time it said that i got mine within the week. EDIT got my despatch email just 1 day after ordering)
Quidco tracks at 20p which theoretically brings the price of each card down to around £9.65.
Dont work for 3DS :(