WASHINGTON -- Don't throw away your old cell phone. You can make some money by selling your used phone.

It's no surprise that Ann Church is an economics major. She was thrifty enough to buy her cell phone second-hand.

"I got the cheapest one," she said. "I think it was $40."

Church is one of 200 million Americans using cell phones, and one of thousands who lose or break their phones each day.

She's also one of the thousands who've realized that new replacement phones don't come cheap.

We checked prices at three popular companies.

Without getting a new contract or a service upgrade, you can't find a phone cheaper than $149 one Verizon store, $119 at a Cingular store, and $149 at a Sprint shop.

MORE ON THIS STORY Telecommunications Research and Action Center Used Cell Phone Sites usedcellphones.com cellularshop.com

So now some savvy customers are capitalizing, selling their old phones on-line and using sites like eBay to trade their older models to customers desperate for replacements.

The phones are cheaper, but they're also cheaper -- someone else's throwaway.

Prices for used Sony Ericssons T-68s range from $7 to $79. $39 for a Sanyo 4900.

But Sam Simon, who runs a national telecommunications research group says when it comes to cells, price is usually no object. People are spending thousands more for phones than years ago.

"People will pay that. There's a group of people that will keep paying and paying and paying, and the phone companies know that"

Crayton Electronics, which operates one of the largest Internet used cell phone sales services, was recently quoted saying its staff tests all phones before re-selling them.

The Washington-based Telecommunications Research and Action Center says the major cell phone companies are now offering insurance on new phones. In most cases, it costs less than $10 a month, the group says.

Considering that thousands of customers are losing their phones each day, this type of investment might be worthwhile.