When I lived in Yuma as a kid we had a day off from school because it rained and the streets had no drainage. That rental must have cost a few bucks. I am glad you changed your $2,500 budget to $5k and waited for an oem battery. Your odds for a reliable low cost maintenance vehicle are much better.
I, normally, don't advise folks to buy older hybrids but you are the exception...already familiar with them so know all the little-known maintenance/repair items. I don't know if I'd ever buy a hybrid that wasn't a Toyota/Lexus....they seem to be head and shoulders better than anything else out there. (Not perfect, but better.)
good luck ... junk yards are filling up with Gen 2 these days so you can get some good deals on some parts.