I found these 2 packs of Magnetic Fridge Frames in WHSmith (my local is Brent Cross in North London) reduced from £2 to 0.99p. On top of that, they were offering Buy One, get One Half Price, so that averages out to 0.75p per pack if you buy two packs.
They hold a 6 x 4 inch photo on the fridge and have a large magnetic surface on the back so are great if you want to attach large things to the fridge (kids paintings etc). There are 2 in each pack.
Great stocking filler for 0.75p