Found this in PC world Romford store. End of line clearance so a perfect product at a cheap price. 25 gb stick would be above £ 10.00
Good for temporary/ long term backup. On Amazon now it is around £8.99 . (by scanning the barcode by pic2shop app on iphone).
Therefore if you need to backup loads of data temporarily ( e.g. Kids photos and videos) this I think is a good option.
The only constraint is you need a blu ray writer.