Yep, Toyota uses Sealed Nickel-Metal Hydride (Ni-MH) batties, I won't bother looking elsewhere. Using a lead/acid battery would be self-defeating in weight alone.
Since these are mass produced batteries their replacement cost should not be more than $2k I think, you've got to look at the "part" these are in the car. They are part of the engine/motor so I would tend to look at them in that light rather than as "just batteries."
In these cars you essentially have two drive systems to maintain so you simply have to expect a higher maintenance cost though statistically speaking it's likely lower. Your mileage may vary.
It just makes me wonder; these batteries are great batteries and are not the latest in battery technology, lithium is even better but the heat and charging limitations present problems I'm sure. It is likely though that the amps these batteries are rated for are larger than they will ever see use in daily life. The web sites don't list that info at a glance, just the voltage (yawn).
Furthermore, with the advances that are capable in this "stop gap" measure for more efficient cars is it reasonable to believe that the government is not pushing them more because they don't WANT them? Conspiracy theory - engage...
I am believing more and more that the conservative administrations in place in our fed and calif state governments are using the future promises of Hydrogen as a smoke screen to distract us from the current gas price problems. "Oh, don't sweat it - in 30 some odd years we'll be done with this whol oil business." In the mean time our youth is being spent supporting big oil.
I'd love to buy one but my cars are paid off and I don't want another car payment, higher insurance and to STILL have to pay for gas. I'd rather simply drive less and take the bus when I can.