Try South Eastern Auto Supplies in Maidstone, Kent, I have just bought a pair of 170ah deep cycle marine batteries from them for £105+VAT each. They were made by Hella, a well respected German manufacturer.
I've got approx 150 Exide 484 batteries. 6 volt 248 AH. Dry charged so no problems shipping apart from the weight. You have to get them filled with acid yourself. Located in Port Glasgow. £75 each or in quantities of 10 or more at £50 each. All plus VAT