I do not think that I have ever seen a rebuilt title on Craigslist for less than KBB. People are crazy.
One Prius battery may have lasted 600,000 miles, but this guy's died after 70,000:
Prius hybrid battery fails at 70K miles, Toyota won't pay for $3700 repair | Copywriting and Marketing Ninja Skills
I imagine that more Prius batteries die under warranty than last 600,000 miles.
Fixing a bad battery is not always expensive. This guy took care of it for $7 and an hour of his time, but I never heard of this particular problem:
Ha! Suck it! You work again you freakin golf cart!