That's an idea for the community.
In a bounty forum you post like in the request one (of the marketplace) but then you say
"i'll put xxx $/€/£ for this".
Then when other people are interested they say:
"i'm on it, i'll pay yyy". A third person might come and say,
"i'm ok to pay zzz but only if it does <this>"
You make the sum, that's the bounty on the feature request.
When a develloper can handle the project, he says "i take the bounty", then contacts all the users to have some kind of contract with them. And then, they get it.
I've seen it on some places (open source projects) and that's nice.
Just an idea
Greetings,
Antoine