NEW YORK -- How much would you pay for an amazing, state-of-the-art light bulb?

Shoppers will be asking themselves that very question at stores starting Sunday -- Earth Day -- when the bulb that won a $10 million government contest goes on sale.

The bulb is the most energy-efficient yet, lasts about 20 years and is supposed to give off a pleasing, natural-looking light. But what separates it from the pack most is the price: $60.

That price reflects the cost of the components, especially the top-notch chips, or diodes, that give off the light, and is the price commercial customers will pay.

But the manufacturer, Netherlands-based Philips, is discounting it right away to $50 for consumers, and working on deals with electric utilities to discount it even further, by as much as $20 to $30.

This means the bulb will cost anywhere from $20 to $60, depending on where it's found. Online, consumers will be paying $50 for each bulb, because utilities don't subsidize online sales.

Congress launched the L Prize contest in 2007, with the goal of creating a bulb to replace the standard, energy-wasting "incandescent" 60-watt bulb. The requirements were rigorous, and Philips was the only entrant. Its bulb was declared the winner last year, after a year and a half of testing.

The contest stipulated that the winning bulb be sold for $22 in its first year on the market.