"Soft and Wet," released by Prince in 1978, was his very first single. Unlike almost any other Prince song, this one has a co-writing credit.

Chris Moon, who let Prince use his Minneapolis recording studio for free, wrote the lyrics. Prince composed the music.

Now, Moon is getting ready to retire. So, he's looking to sell his stake in that song and future royalties. Selling song rights is relatively common, but Moon's method is unusual: He has it listed it on eBay.

"I wanted it to be available to anyone in the world," Moon says. "I wanted to do it in a way that hadn't been done before."

Moon says over the years he has made several hundred thousand dollars in royalties from "Soft and Wet," mostly because M.C. Hammer sampled the song on his enormously popular 1990 album "Please Hammer, Don't Hurt 'Em." Moon says he's hoping to find a buyer who's not necessarily interested in making money, but someone who wants to own a unique piece of Prince memorabilia.

"The idea that it's actually possible to co-own his first hit song and a song off his original demo tape at any price is pretty remarkable."

Moon is asking $490,000 for co-ownership of the song. So far, he's had some inquiries but no serious offers.