Yeah, I guess you could recondition one kinda like how this guy does it. I had never heard of doing that before. Thanks for the info.
I would still opt for li ion even with that though. Lithium Ion has a 2x greater depth of discharge(usable stored power) and 2-3x the lifetime (not taking into account any reconditioning) when compared to lead acid. That equals 4-6x the utility theoretically at around double the cost. That would make li ion 2-3x more bang for your buck compared to lead acid.
But there may be some case, for using a cheaper lead acid on a small scale project. Just be aware of the maintenance requirements of them and the increased cost if you do end up using it on a long term project.