I get Equisorb from Wadswick near Bath, it was £7.35 bale in the spring. You can also try Allenshill, who stock "Thorobed" which is usually a reasonable price, it's just like Equisorb. I normally have a pallet of 36 bales, they are about £7.70 now.
We get Jopack (flax) and this is £7.30 a bag. We have our 4 horses at home and have tried all sorts of bedding and this rots down the quickest! Obviously when you have to get rid of the muck-heap yourself you have to bear this is mind! We take it round to the allotments and they love it!