A Fisker electric car displayed at the Geneva Motor Show in March.

As used car deals go, this is one to make you think twice. Used Fisker Karmas, which sold for $103,000 just a year ago as new models, are now being sold for roughly half price. In some cases, those trying to sell the luxury extended-range electric car on eBay cannot even get bids above $50,000.

Just ask Bill Michlin, a dealer with the Fields Auto Group in the Chicago suburb of Glencoe. He just wrapped up an eBay auction for a 2012 EcoChic version of the Karma with a top bid of $45,100. "I had 2,000 look at that car on eBay," he said. "We didn't sell it because it didn't meet the minimum reserve bid, but it will eventually."