Sorry, you'll never break even. Depreciation hasn't been figured into the mix, not to mention the additional maintainance cost yet to be attributed to these "hybrids" as they haven't been out there long. My engineering buds say new battery packs will be needed at the 50,000 to 75,000 mile range at a current cost of about $5500.
When they started putting catalytic converters in the exhaust pipes they said they would last 50,000 miles. The one in my Chevy is still working at 120,000 miles. That can gets hot, though; you can feel the heat on the floorboards if you sit in the passenger seat.