Ever wonder why office-supply stores will offer a ream of paper or $3 for empty inkjet printer cartridges?

It turns out there is a booming trade in empty cartridges, which are much sought after by the original manufacturers, such as Hewlett-Packard Co. and Lexmark International Inc., and by companies that refill old cartridges for resale.

``There's a world market for empties," said Jim Forrest, an analyst at Lyra Research, which tracks the printing industry. ``Prices vary day to day, just like for any other commodity."

Cartridges that fit popular printer models usually sell for about $7, Forrest said.

This cost is a key consideration for companies that refill and resell the ink tanks, such as Cartridge World. Forest said refillers figure on spending $7 for the container and $1 for the ink, which pushes their cost close to $10 after including labor and packaging.

That doesn't leave much margin for profit, considering that refillers try to keep their prices well below the price of the brand-name cartridges, he said.

Even damaged cartridges are worth something.

Ray Kendall, a Cartridge World franchisee in Grapevine, Texas, has a cardboard box in the back of his shop labeled ``bad cartridges." Some have fouled print heads, and others are missing the tiny plastic tab found on the underside of ink cartridges. But they don't get thrown out.

``I sell `em to the remanufacturers for about 20 cents each," Kendall said.

ASSOCIATED PRESS

© Copyright 2006 Globe Newspaper Company.