I have seen a few people talk about liking Interstate Battery, and the neighbor who bought our old farm kept telling me how great their prices are, so one day when he and I were in their area i went by. I took 2 Skill 18 volt battery packs to be rebuilt, and bought a 6 volt battery for one of my cubs.
The rebuilt Skil batteries cost the same as new ones, but only lasted 8 months (3 month warranty).
The cub battery I bought seemed high, but I had not bought one in several years, and assumed (yeah, I know) batteries had gone up quite a bit. When I got back and did some checking, I found that they had charged me $25 more than one would have cost locally. Now, just 1 week short of 3 years, it has failed. Warranty was only one year for the 6 volt tractor batteries. That makes it both the highest priced and shortest lived tractor battery I have ever owned.