I've got 85ah leisure battery from a local caravan place with 2 year guarantee. 1st one stopped holding a charge after a year and they replaced it no problem , this one must have been going nearly 2 years now with no problems although about a year ago I got another 85ah and keep one in the van and one on charge swapping them every night.
In 3 years i've spent less than £50 on these 2 batteries, obviously prices have gone up a lot since