I haven't checked out the price yet, however if you have any camera store or even The Source (RadioShack) in your area they should be able to order you a box in at an affordable price. I would imagine that a box has anywhere from 5 to 10 batteries, which should last you a Long time.
If they require you to purchase larger quanities, or require a rediciulus price send me a PM. Working in a photo lab means that I get reduced prices, when I buy a box at a time. And I require the same battery for my PZ-20, so I might be interested in splitting a box.
I haven't the faintest idea how much a box at once would cost me yet