is this a good price for a 2010 used Prius?

I'm looking to buy a used 2010 prius II, former fleet vehicle with high mileage. Have been to some dealers and gotten bids for 18,000 (+350 docs) for 44k miles CPO, 16,800(+$500 docs) for 42k miles, 16,500(+$300 docs) for 53k miles, and now found one from an auto repair shop for 15,400 for 52k miles (no docs fee other than reg fees).

all the non-CPO vehicles appear to be in the same "very good" KBB condition, and have clean carfaxes. the price variance appears to be from the mileage and auction purchase dates, as used prius values have gone up and down in the past year.

I'm planning to go for the cheapest car and have it inspected by an independent dealer prior to purchase, to confirm the "very good" condition. Any thoughts? We live in MA.

I am hard on cars (not while driving, but I tend to scrape the sides/fenders when parking) so I didn't think it made sense to invest in something new as I would quickly depreciate it.