ive used the cheep asda one and i dont like it, it doesnt always soak up the pee and the cats end up with wet feet! lol the cheep tesco one is slightly better, and the next price tesco one isnt bad, i prefere Sophistcat or sommin like that, but only the pink one! its very absorbant, they turned their noses at 1st, but they get on with it fine now. its £4 for a normal size smallish bag, but you can get one of the big ones for £9 which is like 4 times the amount of a small one, i get this from the local pet shop.
I would suggest if your trying new to you, get a small one 1st, we dont all like the same litter after all