Compare the price with the Lotus Elise on which the Tesla is based and it doesn't look quite so attractive.
The Tesla costs $50,000 more than the Lotus, for which you get similar performance, but higher weight and less agility.
If you take the $50,000 saved by buying the Lotus, you get 12,500 gallons at $4 a gallon. The Lotus gets about 23 mpg, so the money you saved will be enough for about 288,000 miles of driving. And that's before you take in to account the costs of running the Tesla.
And of course neither car is likely to last that long.
You can certainly find alternatives to gasoline, they just aren't as good and cost a lot more. That's not going to change until someone makes a major breakthrough.