The Leaf would cost you about 30-37K before Federal Tax break.
Unless you could charge it at work, you might run into problems with the battery range, especially in the winter (less of a problem if you live in a warmer climate).
A plug-in hybrid (I think there is a Prius model, as well as the Volt) might be a better choice.
Personally, I prefer diesels - I drive a 2002 VW Golf TDI - I average about 40 MPG driving from a NYC suburb into Manhattan daily - averaging 39-40 mpg. Car is just about to turn 200,000 miles and has been fairly economical to run over the 12 years I have owned it. A new Golf TDI runs about 27K, the Jetta TDI is less. Great drivers, and nicely appointed cars, to boot.