Prius 12V battery needed?

So my last battery picked up was an Optima Yellow top in 2017, battery is showing big time signs of not holding charge for any length of time and I was told that the HV battery being wonky is not a cause of it. But I'm getting a bit of sticker shock now. I got the battery for roughly $140 (pre tax) back then, and I realize that it was a good price at the time, but now I'm seeing the price as $100 more than that, hell even Amazon price shows only one at over $600! Which I'm guessing is due to the battery being discontinued?

So what's a decent enough battery to get these days? A quick look shows everything at $200+ from various auto stores, but is there some secret back room deal price somewhere that's a bit more reasonable for something? I don't need it to last 5-6 years, it's a 15 year old car, that I feel is going to get very expensive to keep up with replacement parts needed. Would like to squeeze a few more years out of it sure but if I gotta let it go, I'll let it go.

Is the whole global supply chain issue crap the reason why batteries are this expensive? Or did they just have a relatively big jump in price across the board because they can?

 

How much current draw do the computers actually need? Seems like throwing any old 12V battery into the car is something that should work, you just need to fit it in the space provided... or make a bigger space!

And why max Ah? Does that 12V battery do anything else other than turn the computers on? I mean obviously it also does things like wipers/windows/locks/etc, but is it just a matter of making sure enough capacity so it doesn't discharge too much between turning the car on?

 

Ok, I'm sold. I don't see any specs on the terminal thread size on that ebay page though.

 

Alright, so far so good. Messed up with the bolt size, not sure what went wrong with my measuring but somehow I ended up with 40mm long bolts and while I was tempted to just have a stack of a dozen washers, I opted for smaller bolts. Which did turn into a mixed blessing because the battery dimensions are slightly taller than the standard prius battery (or Optima) as a result the bolt that holds the clamp that secures the battery didn't quite reach the floor, but 40mm M6 bolt to the rescue!

Now the downside is that the little plastic panel doesn't sit flush anymore, although it's not a huge deal to me, it sits "good enough". Also have no idea where to put the little tube that plugged into the original Prius battery, but I never plugged it into the Optima battery, so no harm no foul.

But car started up just fine, so hopefully that is the last of the 12V battery issues I have. Now onto the HV battery.