I'm all for it. The more people who buy into electric, the more gas is left on the planet for me.
The Model S *might* hit the similar cost point. We'll have to see how it all works out when they actually deliver a car. The Roadster certainly doesn't come close to that point on paper.
Let's look at it versus the Lotus Elise and plug in some ridiculously conservative figures so we can be certain:
$101500 Tesla Roadster MSRP - $51845 Lotus Elise MSRP = $49655 difference
$49655 saved / $5 gallon = 9931 gallons (let's assume gas costs another $1)
9931 gallons x 20 mpg = 198620 miles (let's assume a "spirited driver")
198620 miles / 15000 miles/year = 13.24 years
13.24 years is the break-even point on a Tesla Roadster.
Start factoring in that the battery life is seven years or that Tesla recommends you have 3-phase service and it gets worse.
Almost, but not quite there yet.