My (gas-powered) 1999 Toyota Tercel finally had to have its battery replaced this past fall. Mind you that is probably a pretty good record because my cars don't get driven a lot. It's 9 years old and has less than 100 000 km on it. I got a Canadian Tire brand battery for less than $100.00. It would have cost more if I'd bought a Toyota brand battery. I doubt that hybrid cars have batteries available from anyone except their manufacturers yet so they do probably cost more because of the brand name/inability to get them at any old hardware store.

I hadn't heard that hybrid batteries cost $8000.00 - you may want to look into that. The bad thing I had heard about hybrid batteries is that they are not recyclable (yet) so when you do trade them in for another battery they create toxic waste that has to be disposed of.