Here's an article that shows good promise for longevity of the NiMH battery packs.
Motor Authority » Toyota Prius taxi tops 340,000mi, dispels battery myth
"Two of the older examples have managed a lifespan of 350,000km (218,000mi) and 550,000km (341,000mi) before needing replacement of their nickel-metal hydride (NiMH) batteries. The only problem even at the end of their battery pack service life was a low voltage reading."
So if you ended up buying that used Prius with 125K miles on it ... and have to replace the battery pack in less than 100K miles like they did on one of the older cars in service ... you are looking at tagging on anouth $3,000 to that cost ROI.
An interesting Newsweek article states:
"Still, hybrids don't hold their resale value as well as their gasoline powered siblings."
Source:
http://www.newsweek.com/id/138808/page/2
A really funny article about why you never ever want to let your Prius battery die completely:
http://www.greentechmedia.com/articl...-ever-741.html