When you've got bad kidneys, there's no telling the heights you'll go to get a new one.

After languishing on a transplant waiting list, a Salinas, Kan., couple decided to take matters into their own hands. Sharon Nelson, 73, and her husband James, 70, rented a billboard on Interstate 70 in Jewell, Cloud County to advertise Sharon's plight. Then they went out to the highway, where James climbed up the board to paint their message.

"It was a particularly cold morning that day. I grabbed a chair and sat there making sure he wouldn't fall from that ladder," said Sharon, who must undergo frequent dialysis.

Her husband, a Vietnam veteran and former mural painter, borrowed a 12-foot ladder and painted "I Need A Kidney" along with his phone number on the white billboard.

Sharon Nelson told ABC News they got the idea from a nurse at the Mayo clinic in Rochester, Minn. The nurse said she knew a Milwaukee man who had found a donor for himself after renting a billboard, Nelson said.

Nelson has been in and out of hospitals since she was diagnosed with bone marrow cancer in 2008, and since 2009 she has been on dialysis because the cancer treatment damaged her kidneys.

In 2010, she started considering a transplant and the search for a potential donor started. She was then approved for a transplant back in February.

However, the search for a matching donor hasn't been easy since Sharon has type O blood, and she can only receive a kidney from a donor with the same blood type, Nelson said.

Nelson said numerous people have come forward looking to donate a kidney-she doesn't know exactly how many-but so far none of the offers has crystallized. "We've been overwhelmed by the generosity of people," Nelson said.

One problem is that some of those who have offered have been sick in the past with conditions including tuberculosis, COPD, and heart problems, and that disqualifies them from becoming donors, she said.

When asked if being on dialysis has been harder than beating cancer, Nelson said that it has indeed been difficult.

"Basically with the cancer I took the chemo that was required," Nelson told ABC News. "I just took the chemo and went about with my daily life."

But having to go to dialysis three times a week now dictates pretty much all of her life and that of her husband's.

"We got to check the calendar to see whether it is a dialysis day or not because if it is, it's out of the question," Nelson said.

Until the right donor comes through it's just a matter of waiting, so she and husband can move on with their lives, Nelson said.

"If I get the transplant there are some things that we want to do," Nelson said. "We will be able to visit family and friends easier. We won't have to think about what time of the day it is to do something."

According to the National Kidney Foundation, over 96,000 people in the United States are waiting for a kidney transplant.