Prius has a timing chain, so I'd take anything else they say about it with a grain of salt, unless they have receipts.
That price is actually pretty in line with a lot of Prii I see in this area with similar mi/km and age. Vermont has very strict inspections, and most cars which have seen 10+ winters are just about ready to leave the run, from their undersides rusting out.
Some local Prii:
$500, 320k km:
https://vermont.craigslist.org/cto/d...561164447.html
$1700, 288k km:
https://vermont.craigslist.org/cto/d...577396831.html - won't pass inspection due to rust
$3000, 240k km:
https://vermont.craigslist.org/cto/d...589942935.html - claims it has had anti-rust coatings applied every year
$3250, 270k km:
https://vermont.craigslist.org/cto/d...565546348.html - claims new battery
~
That's not to say your find is a bad deal, or that you shouldn't get it. I'm leery of buying older cars around here though due to rust - I shop in the south and drive 'em up.
As far as electronics, Prii are nearly bulletproof, and a battery isn't all that expensive (or difficult) to refurbish or repair, so long as not every cell is dead.