Firebox seem to be the cheapest site offering the Topfield TF5800PVR 250GB for £259.95 + £3.95 postage
This can be reduced to £256.90 with the £7 voucher here: http://www.hotukdeals.com/deal/12152/free-7-voucher-for-firebox-com-mini
Also you can earn 10% cash back using Quidco bringing the total down to £231.21!
Cannot find this anywhere else this cheap! I ordered one just now but they are out of stock till the 18th! Nevermind I can wait!