Start with leadrefs.com, if it isn't free, invest a little if you can. Pen a good email, start contacting end users.
It looks like it's widely used for an array of businesses. I'd ask for 10k and negotiate from there, but you may not get many bites. Otherwise I'm sure you can sell it fast for 2-4k.
Good luck. If you want hands off I'm sure there are a few members here that would attempt to broker it for you for 10-20%. Like a real estate agent you'll get the best possible price if you're willing to pay the commission.