** Preowned ** MS 120Gb hard drive for the Xbox 360. At the time of posting there were 43 available for online ordering at the time of posting. If you're lucky enough to have a CeX local to you then you can try and see if they've got some in stock so you can get it sooner.
CeX still gives "12 months warranty on all items" for those that are worried about it being preowned.
This will not come with a transfer cable so if you're upgrading from an old 20Gb or 60Gb (and want to keep your save games etc) then you can phone MS and ask them for a free cable. Apparently it will arrive in around about a weeks time from Germany.