best place to buy prius battery

It’s a risk, but has been done.
Best place is the dealer

 

Gen 4-Gen 2 Battery swap.
Gen 4 cells in a Gen 2 | PriusChat
Gen 4 battery for gen 3 | PriusChat

Car-part.com, input your zip, 2017 Prius, look for battery, select nimh.
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Sample 2020 Corolla battery, 27,000 mile, around $1000-1100

 

For new batteries, I would suggest newpriusbatteries (or any other vendor of cylindrical 14.4 V NiMH packs).

 

I bought a junkyard battery from Wagner's Auto salvage in Durham North Carolina from late 2015 for my 2010 solar roof JBL leather thing Gen 3 It's been in there about 4 years Not a problem since now it's starting to have break actuator codes looking to see what I can find for that I think a lot of those Gen 3's are interchangeable for that part too.

 

Two things batteries don't like; sudden jolts and heat. Pulling a junk yard battery is a 'crap-shoot'; sudden jolt - but it may work. Off-Roaders swear by the Optima batteries with cylindrical cells. Less prone to killing the battery while they're rock-hopping.

If you have limited tools and skills, don't want to mess with an unreliable car; ChrisFix on youtube has a decent video on a new battery replacement job. Should take you less than a day.

Hope this helps.......