Last time I inquired of a merchant local to my home, (North West Herts), the rate I was quoted was very much less than any quoted above, and from memory would only have yielded around £6 per 110 Ah battery. So I didn't bother at the time. This means I now have about half a dozen 110 Ah batteries stacked outside, as well as a couple of much smaller car batteries.
Perhaps I should try again? Although our boats are berthed in the Weedon area, I really don't fancy carting all these batteries up there, as we usually travel with 2 large dogs in the boot, and I don't fancy staking batteries on the rear seat..