So I found this place that sells used car batteries for $25. It's a battery shop and he said he runs them through tests to ensure they're not crap..seems believable since they probably have the equipment. I read a little about batteries/ratings/age so I knew what I was buying. The thing is, I'm wondering if would be a worse deal because they don't last enough to justify the price.

I can probably buy a new battery for about 80 from a retail store and keep returning it to get a new one if something bad happens to it, so I have that insurence. I'm not actually sure if I'm keeping my car super long term( more than 3) years

Has anyone bought a used battery? Is it a bad idea?