Faced with financial problems, a Chicago-area man turned to the Internet and took the drastic measure that countless others have: offered to sell an organ.

"I was kind of joking about it one day at work and I thought why not?" said Michael Nelson of Aurora. "I could help someone out and they could help me out at the same time."

The 40-year-old said he received numerous hits on his Craigslist ad -- one kidney in exchange for $30,000 -- which ran for about a month. Before he knew he was corresponding with NBC Chicago, Nelson said he was struggling financially and that selling his kidney would alleviate his problems.

"I did some research and there's no difference between having one and two," Nelson later explained. "There tends to be no adverse side effects. ... Three weeks of lying around, that's not bad. Not a big deal."

But it is a big deal.

Knowingly acquiring, receiving or transferring any human organ for human transplantation in exchange for money or consideration is against the law and can be punishable with prison time, a fine of up to $50,000, or both. Chicago law enforcement agencies said they’ve never made any arrests in connection with illegal organ sales but said any allegation would be investigated.

Despite the potential penalties, NBC 5 INVESTIGATES found hundreds of people in Illinois and across the world who were willing to sell kidneys for thousands of dollars. We exchanged e-mails with individuals claiming to be organ brokers and doctors open to performing the illicit transplants.

And there is demand. Hundreds of thousands of people currently wait for organ transplants, fueling a black market of human organs.

"It's tough to hear about people who could buy a kidney when there's people like myself waiting patiently for years to receive one," said Daniel Perez, who was diagnosed with kidney failure about two years ago. The 35-year-old Logan Square resident has been on a waiting list for 18 months, and until there’s a compatible donor, his four-hour, three-times-a-week dialysis treatments are his only legal option for survival.

"I think that all of us that sit here, we know that hopefully we are getting an organ through the network and nobody thinks about the black market,” said Perez. “Everyone knows it exists, but no one really talks about it.”

Patients like Perez have to wait on average three to six years for an organ. It's that kind of desperation that has led some to extreme measures to circumvent the national organ donor list.

Dr. Yolanda Becker, the director of the Kidney and Pancreas Transplant program at the University of Chicago Medical Center, said she sees first-hand how the demand for organs has increased while supply has remained stagnant. Kidney failure has become nearly epidemic in the United States. Additionally, dialysis patients are surviving longer, meaning more are candidates for transplants.

"There's clearly a shortage of appropriate donor organs for a variety of reasons," said Becker.

The U of C program has about 650 patients on the list for an organ, and there are more than 122,000 people nationally on the wait list. In Illinois, statistics indicate about one patient dies each day while on the waiting list for an organ, according to Kevin Cmunt, the president and CEO of Gift of Hope, an Itasca-based non-profit that coordinates organ and tissue donation.

The disparity between supply and demand for organs has spurred talk within the medical community about the possibility of creating state-wide pilot programs that would permit the controlled sale of organs. Congress has so far been reluctant to change the 1984 law.

In the meantime, more than one human organ is sold illegally somewhere in the world every hour, according to a 2012 World Health Organization report. Most of those organs are kidneys.

"The way it is set up, the right way, I guess you sit here patiently and wait," Perez said during a recent dialysis treatment. “And others who have the means just go and buy one like they are on Amazon or eBay. It kind of blows my mind."

And so Perez continues to wait.

"I just try to live my life and when it happens it will." He said. "I try not to think about the transplant too much. I just try keep my life as normal as possible."