I have just bought some cot bed fitted sheets from asda
for cot-bed size they were 2 packs of 2 (so 4 fitted sheets in total) for £12
cot size were a little bit less. (I think one pack was £8 or £9, so 2 packs was a really good deal)
I am amazed with the quality really thick soft nice soft 100% jersey cotton. I have a 13cm deep mattress and it fits with ease, no problem, all the way under
I have used mothercares equivelent on a normal size cot mattress and it hasnt really even reached the bottom of the mattress, + the asda fabric seems thicker and much softer and nicer and better quality.
Also i have washed the sheets at 60C and they fit fine, so not as if new and will shrink in wash, i would have thought thats already happened.
Pretty sure Asda do a whole range of bedding and if the other items are the same quality as the cot bed fitted sheet then you shouldnt be disappointed.
I bought a couple of fitted cot bed waterproof mattress protectors too, from asda. I think they were £6 each and again, no complaints at all about the quality. I was very very impressed (and couldnt even find any cheaper on ebay!) (+ much much nicer than Tesco's equivalent that i also looked at and rejected!)