Anyone interested in a Chevy Volt can put their name down on the unofficial, no-deposit waiting list here. The price is expected to be about $40,000 not including a possible $7,500 tax credit. That's still pretty steep, especially for a compact four-seater, so I'm not expecting GM to move nearly as many copies as Toyota has of its $22,000 mid-size, five-seat Prius.
Computing savings from using electricity instead of gasoline is nontrivial given the somewhat complex rate structure of electricity. Martin Eberhard, a founder of Tesla Motors, posted his thoughts on the matter here. Using his figure of 3.6 cents/mile, you'd save roughly $700 per year (assuming 15k electric miles/year) in fuel costs compared to a Toyota Prius (8.2 cents/mile assuming $3.75 gas and 46 MPG), yielding a payback time of 15 years. However, the likely reason most buyers will choose the Volt is not the financial savings from fuel costs, but rather the accompanying reduction of oil consumption, CO2 emissions, and their associated negative externalities.
I've previously mentioned concerns with the duty cycle of a PHEV's battery (deep discharge) and its impact on longevity. As I understand it, the Volt will only allow discharge to 30% capacity, then maintain that state of charge using the generator until you plug it in again. Reducing the range of discharge during normal operation should reduce wear on the battery, though by how much is unclear. Since concern about the battery is one of the top reasons customers are hesitant to purchase a hybrid, GM is planning on warrantying the battery for 10 years/150,000 miles. Bob Lutz has indicated the replacement cost of each battery is actually already factored into the MSRP of the vehicle: "We're being conservative on battery life. For our cost calculations we're assuming each car will need a replacement during the warranty period."