Sooner or later even the best carpet needs to be replaced.

And good carpet isn't cheap; it's a major investment, so you want to get the most for your money.

When you buy new carpet, you want three things: good service, good price and quality installation. You don't need to pay top dollar to get top-quality. But in these tough economic times, you do need to know where to shop and how to shop.

It's easy to assume that all carpet stores are basically the same -- same brands, same styles and same ballpark price. The fact is, there are huge price differences from store to store.

For its current issue, Puget Sound Consumers' CHECKBOOK magazine comparison-shopped Seattle-area carpet stores. They priced the same job, same carpet and pad, plus installation. Price quotes ranged from $2,242 to $5,321.

"That carpet is that carpet wherever you buy it," said Robert Krughoff, president of CHECKBOOK magazine. "It's important to realize the particular make and style may only be on the floor of one shop, but that doesn't mean that many other shops couldn't order it from the factory. So you just call and say, 'This is the make and style I want, and the pad I want. What's your price?'"

You can have the best carpet in the world but it if isn't installed properly, you've got a botched job. In it's survey, CHECKBOOK heard a lot of installation complaints.

"'They didn't get the carpet seams right. They damaged my furniture. They damaged my walls. Everything looked wrong.'" said Krughoff. "So installation is a big thing. You want to find a place that does good installation work."

CHECKBOOK gathered customer ratings for 46 carpets stores and installers.

Only one store got top marks for service, price and installation: Vogel's Carpet Service in Seattle.

Two stores got top marks for service and installation: Craft Carpets in Federal Way and Décor Carpet One in Renton.

Abbey Carpet of Tacoma was highly rated for installation and price. And Carpet To Go in Bellevue scored well for service and price.

A few more carpet buying tips: buy a small sample of the carpet you've ordered. That way when the installer comes to your house, you can quickly make sure you got what you bought.

If you're buying a remnant, take a magic marker and write your name on the back of the carpet before you leave the store.

Make sure the contract or work order spells out who will remove and haul away the old carpet -- them or you.