I wonder how much of that cost is the battery cost and how much is the licensing agreements and so on to use the batteries, Toyota has contracts with Panasonic to make their battery packs and I would imagine that those contracts have some weird non competition agreements in them as well.
Lithium batteries have also been dropping a great deal in price, the lithium batteries on my desk right now cost me $316 per kwh and I'm not a large auto producer.
EV Comparison says that NiMH batteries cost $450 per KWH