I bought mine a few weeks ago but went to PAH tonight and they still have them in all the sizes. They are actually in the dog bed section and are £9 reduced from £24.99 for the small one (big enough for 2 kittens or 1 large cat). They also had medium for £14 and large for £19 or large mattress for £14, all reduced from some equally ridiculous price! Out of all the beds they had in the entire range I think these are actually some of the nicest, they are very squishy and have nice high sides.
Here's a pic of the 'small' bed / shameless attempt to show my new baby off