Ask HN: Is it possible to sell an app before it launches?

I've been working on a side-project that is an anonymous posting app for controversial issues. I've checked out a few marketplaces online to sell source code but there seems to be nothing that is too helpful. I'm interested to just sell the entire app to someone. I believe it's too early-stage to even think about selling it to a company. Is this plausible? And if so, how would you recommend I go about this? I built it to learn- not to get into the anonymous app business!