How old (model year) and much mileage would you personally buy a used Prius and feel comfortable? And how much is a new battery outside of warranty these days in US dollars? I thank you.
I think it would all come down to price, how well it was cared for and maintained and such. Battery replacement shouldn't be a huge concern unless you're over 150k-200k miles. Even then used OEM batteries are available for around $500-1000 salvage on Ebay and elsewhere...cheaper than a transmission.