The figure quoted in 2010 for cost of the Leaf batteries was $375/kwh. For a 24kwh pack, that's $9000 for manufacturing cost. A more recent guess was $310/kwh. Deloitte has observed that the historical rate of improvement in battery technology has been something like 5%. Another report from Citibank in 2009 said something similar (see http://ourenergypolicy.org/docs/9/All_Hail_the_Electric_Car_-_Citi__3_.pdf). If you forecast a rapid 20% rate of price drop for the next three years, it would still have a manufacturing cost of $4600 after three years. The retail cost including installation for a new battery pack would be considerable.
Consider that the car retails for $33K at present. A prius, civic, and VW Jetta TDI all sell for under $25K. A huge part of the cost for the Leaf is the batteries. I wouldn't count on batteries being cheap in three years.
