"I certainly hope and intend to get better—but if I don't, I'll at least have peace of mind," he said about making sure his family isn't stuck with the bills.

MESA, Ariz. — Ever since he can remember, Robert Letscher has been enthralled with comic books. The 55-year-old turned his passion into an online career.

“It’s how I paid for this house,” Letscher said while sitting in his Mesa living room.

Over the years, Letscher has bought and sold comics of all varieties and price points but always held onto one very special collection of X-Men books.

"It’s the most comprehensive and highest graded of any X-Men collection ever assembled,” Letscher said.

In other words, his collection is the most valuable complete set in the world.

"Things have actually gone up in value almost every year since I was a little kid. They were 12 cents back then and now they can go for over $100,000 or more for the first X-Men comic in nice shape."

Until now, the books were more sentimental than anything, mostly collecting them for personal pleasure and to help bond with his daughters. Letscher’s mentality changed however in 2018 with a grim diagnosis. After running some tests, a doctor told him something nobody ever expects to hear.

"'I just thought you wanted to know you probably have cancer.' And then just walked out the room. And I'm like, is this really happening?" Letscher said.

Cancer had been spreading through his esophagus for almost a year at that point. Someone with his diagnoses is only given roughly a 25% chance to survive five years or more.

"I certainly hope and intend to get better—but if I don't, I'll at least have peace of mind knowing I didn't leave them with a bunch of comic books and no way to pay for the medical bills which are still cascading in,” said Letscher.

Robert does have medical insurance through his wife’s job, but deductibles and co-pays are adding up, and it didn’t take long for him to realize the importance of his prized possessions.

"It wouldn't really surprise me if it eclipsed half a million in all total,” Letscher said about what he is expecting from an online auction through ComicConnect.com in New York. The bidding for this rare collection starts on Monday, Aug. 19.

The can browse the collection now by following this link.