In this specific case I would sell at a lower multiple to someone in the niche community. The amount of money to be made by selling someone who wants to exploit the userbase isn't worth tarnishing my reputation and subsequently shooting future projects within the same niche in the foot.
I've had an interest in taking on a project for a while and your comments have sparked something for me. I'd be interested in chatting with you about your project if you'd like. I'll buy a coffee/beer/tea/beverage of choice just for the trouble of a call. Contact info in my profile if you're interested!