People are going to have lots of answers, and I feel like they are likely correct, but the best way to answer that question is to just post it on a site like Flippa with a high minimum threshold purchase price. This might bait enough bids out if it really is as valuable as they say. Alternatively, you could research what keywords / services it relates to, send some emails to companies or agencies with a focus on those niches, and see if any ballpark offers to you. Beyond that, it's really hard to tell.