I'm selling my plugin Automatic Post Tagger ( https://wordpress.org/plugins/automatic-post-tagger/ ); I no longer have the time to maintain it. Lots of people would like to see this work with bbPress, BuddyPress, WooCommerce etc. If you win the auction, you'll get dev access to the plugin and also receive the version that's currently in development. Payment must be made via bitcoin only.
The userbase and reputation follows automatically, almost instantly, when your project is already slowly dying and someone else is continuing the developement. This is something you should GIVE away to a competent developer. If this generated any form of revenue already, then sure. But as is it's just an open source project with a promise that someone might buy a possible extension. Selling this as is defeats the whole purpose of opensource.
Based on the number of new feature and custom modifications requests I've received I'm guessing that there is some potential to generate revenue - which is also what my Patreon page suggests ( https://www.patreon.com/devtard?ty=h ).
That's great. But unless that revenue is already present, then your just going to end up with a buyer who either makes this a paid plugin straight away and doesn't give a shit just hoping to get his investement returned, or keeps it free but doesnt spend a minute developing it. I'm assuming you don't want either for the plugin you will forever be named "Founder" for. It would be a completely diferent story if you already had revenue.