I used to joke when the Prius first came out, that owners didn't have to fill them with gas for the first year because they were powered by pure smug self-satisfaction.
At the time, I was impressed with the technology, and thought it was great that Prius was bringing economies of scale to the automotive use of electric motor/generators, batteries and power-control circuitry since most or all of those would be important in the future. I wasn't going to pay a premium to help toyota with their R&D though.
Now, it's a lot easier to consider a hybrid. When I was shopping for a new car, I was worried about my exposure to rising gas prices. I figured the payback period, at $3.00/gal, and then at $4, $5 & $6. By the time I bought the car, gas was already $3.50/gal and now less than 6 months later, it's already well over $4.
By the way, I'm pretty sure the net energy inputs going into the production of a Prius have been declining sharply as economies of scale have improved.