Oh and just seen this on Eurogamer:
"Online, the cheapest place to buy a 3DS XL is at the virtual version of Sainsbury's. The supermarket's online base price is £179.99, but you should be able to whittle that down to £161 with the voucher codes SETENJ12 or SECOSMO. You'll have to sign up for a new account to unlock the offer, however."