Alright, let's dial down things a little. pupsik I appreciate your insight and thoughts. In my experience, throwing more complexity at a problem isn't usually the way to solve it. However, I agree with @hrvoje_hr there's a bit of a visibility issue for developers to find work, and for feature requesters to find developers to do said work. For the latter, we've added https://flarum.org/partners, but it's not exactly exhaustive.
I think the ability to assign bounty values to discussions could definitely be interesting, and shouldn't be too difficult. With that in mind, low cost + possibly good return means it's something worth considering. That being said, I think this should just be a bulletin board of funded feature requests rather than a payment coordination / aggregation system, since that gets into a lot of complexity.