A "green" light bulb that won a U.S. government award of $10 million may have trouble attracting buyers because of its $50 price tag, retailers say.

The light-emitting diode bulb made by Philips won the award, called the "L Prize," announced by the government last year for the first manufacturer that could create a "green" but affordable light bulb, The Washington Post reported Thursday.

The prize, Energy Secretary Steven Chu said at the time, would give the lighting industry an incentive to offer costly LED bulbs at prices "affordable for American families."

Retailers said the Philips bulb is likely to be too expensive to have broad appeal, with similar LED bulbs available at less than half the cost.

"I don't want to say it's exorbitant, but if a customer is only looking at the price, they could come to that conclusion," Brad Paulsen of Home Depot, the largest U.S. seller of light bulbs, said. "This is a Cadillac product, and that's why you have a premium on it."

A Philips spokesman declined to talk in detail about the bulb or its price, the Post reported, but said the L Prize bulb costs more because, as the competition required, it is more energy-efficient, running on 10 watts instead of 12.5 watts, and is also brighter, displays colors better and lasts longer.

But the price still remains a hurdle, many say.

"Are there many consumers who will say a $50 bulb is affordable? I don't think so," one retailer familiar with the new bulbs told the Post.