(Image Credit: Marc A. Hermann/AP Photo)

By Chris Kilmer and Gio Benitez

Modern workers have struck another form of "black gold": printer toner, part of the $50 billion per year companies may lose to employees stealing from the office, according to the U.S. Department of Commerce.

Marque Gumbs is out on parole after serving 18 months for stealing $1.5 million worth of toner from New York's Memorial Sloan-Kettering Cancer Center, where he worked for years in the shipping department.

In his first media interview, Gumbs told ABC News' Gio Benitez a stranger made him an unlikely pitch: order expensive toner on the hospital's dime, then sell them right out the back door.

"Whoever was coming to get it would just meet me downstairs at the loading dock, and then they take it from there," Gumbs said.

Watch the full story on "20/20: Work Wars: How to Win Them, How to Wage Them" Friday at 10 ET.

"They call me back with the money in a potato chip bag," he went on. "Like, $3,600 for that one day."

Those potato chip bags full of cash paid for fancy clothes, jewelry, even an apartment at Trump Plaza in New York.

" I bought a BMW, white X-6. I had a Range Rover. I had a 335 BMW Coupe … [T]aking my family away on trips … Vegas, went out there at least four times a year. Cancun, Mexico, the Bahamas, Miami. You name it, I was there."

Gumbs got caught when his bosses realized he had ordered toner for printer models the hospital didn't even use.

In another example of the stolen toner black market, prosecutors in Washington state say former Office Depot employees Dion Alexander and Kenneth Ngugi made off with more than $500,000 of toner from the company's warehouse. Ngugi sold the toner on eBay and gave Alexander a cut of the profit. Alexander was sentenced to 16 months in prison. Ngugi failed to appear in court; police say he's a wanted man.

Former Santa Fe, N.M. sheriff Greg Solano got jail time and four years' parole for stealing $13,000 of toner and other office supplies, which he, too, sold on eBay.

Gumbs was remorseful. "I know I hurt a lot of people, and I want to apologize to the hospital, too," he said.

The most disappointed person was his mother, Gumbs said. "Because she didn't bring me up like this. It was just something that I wanted to do to make everybody happy."