Asda do a pack of 20 for �3.69 (I think) always on offer at 3 packs for �10 (i.e. �3.33 each). They were until recently �3.00 per pack, which was great while it lasted! My daughter liked these although they are not as pretty or streamlined as the more expensive brands.
I know they also sell cheaper ones in Aldi, I never got round to buying any but they looked okay.