I've read pricing on EV lithium ion battery packs is at around $450/kWh... that'd put it between $18,000 and $38,250 depending on which model you buy. It's definitely the largest cost component of the car.
Yes, the batteries are very expensive. Doubling the battery capacity adds $20,000 to the cost of the car. Most likely the batteries will have a 5 year lifespan, so the amortized operating costs of the batteries may be around $20,000/5 = $4,000 per year. There's also the issue of the environmental costs of the manufacture and of the disposal. These factors are seldom mentioned or discussion tolerated these days, buried under talk of going green and the low cost of the electricity to recharge.