I have two friends with a Prius. One has over 100k miles on hers and has not had to replace anything. The battery did go dead in her driveway [the one that makes all the other stuff work – not the regular battery it has] and her husband charged it. No problem since.
Another friend has less miles and her car stopped on a bridge with all the lights going off. It was this same battery problem. She was towed in and they had to put a new one is they told her, which they did for over $400.
Seems there's some misrepresentation out there if these batteries can be charged … or if there's a price difference between $438 and “a few thousand dollars.”