In some places, you almost can't afford not to buy an electric car.

Adding regional incentives to state and federal incentives can cut the price of some electric cars nearly in half and make them cheaper than some used cars or the most basic of new gas models. Consider that electric cars never need gas or oil changes, and buyers can come away with lower monthly costs than just buying gas for an older car.

These state and regional incentivesalong with occasional special fees charged on electric-car buyers—can make or break the purchase of an electric car.

The best example currently is in Denver, incentives from a local dealer and utility company pile onto the $5,000 Colorado tax credit, and federal tax credits to cut as much as $19,500 off the purchase price of a Nissan Leaf. That's more than the base MSRP of a Honda Fit, a Hyundai Elantra, or a Mazda3.

As in Denver, local energy companies often play a big part in such discounts. Xcel Energy, a local Colorado utility, has partnered with Tynan's Nissan in Aurora to offer the program. Xcel and Tynan each kick in a $3,500 cash incentive, which, combined with the Colorado state tax credit and the $7,500 federal tax credit, can get buyers into a base Nissan Leaf for as little as $11,665. 

Payments on a five-year loan at 5 percent interest could be as little as $220 a month. That's less than some Denver drivers may pay for gas every month. 

Colorado is working hard to spread electric cars among its population to improve air quality in the region. Denver may be the most compelling place to buy a Nissan Leaf, but other regions also offer compelling deals.

- Buyers in nearby Fort Collins, Colorado, offers buyers a $9,000 group-purchase discount on top of state and federal tax credits that can make Leaf purchases even cheaper than in Denver.

- Connecticut offers electric-car buyers a $3,000 state tax credit, and some state utilities add thousands more. Norwich Public Utilities offers a $1,000 rebate for those who buy or lease a new or used electric car.

- Oregon offers a tax incentive of $2,500, which buyers can add to a $3,500 rebate on Nissan Leaf purchases through the local utility Portland General Electric.

- State, county, and municipal tax exemptions in Seattle can add up to more than $2,500 per car.

No matter where you live, it's worth seeking out these local discounts and incentives. They can make choosing an electric car even more affordable.