I've had excellent experience with the over-the-counter batteries WalMart sells. As you said, Tom, usually much less expensive than tire changer shops or parts stores, and, their warranties are quite good. Arizona heat eats batteries, but when I've had a failure within the warranty period (I always shoot for at least three years), they swap out a new for the old with no questions asked. I went several years with a couple of different cars on one battery purchase apiece.
I have a WalMart 24 series battery for my '78 Malibu. It shows no sign of giving up. I don't even remember how old it is.
And, I endorse what Bill said . . . like tires, nearly all (wet cell) batteries come from a couple of manufacturers who slap different labels on them depending on who's buying this run. There's very little competition left at the manufacturing end, it's all at the marketing end where different sellers push the same product.
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