I got a couple of the same 130ah Explorers from Alpha a couple of years ago and I've been chuffed to bits with them. Same footprint as my previous 110s, which was a real bonus with locker size. I think I paid £88 each back then with our WC discount. I know there are some amazing batteries out there and I confess to drooling over the new lithium ones but they're a huge investment in one fell swoop. My instinct is to keep things simple and it's not too huge an outlay to replace them when necessary.Try Alpha Batteries. Their pricing on Ebay can be cheaper than direct, as the WC discount has been reduced to 5%.
I just replaced my two 110ah batteries with two Explorer 130ah - a deal at £189.99. The new batteries are actually smaller than originals but slightly taller ,which worked fine in the storage locker.