Looking at the Bountysource docs, it looks like users can offer bounties. Do you know if it has a Github integration that allows developers to post some sort of price schedule, or to request a bounty on a given issue?
Edit: It looks like there are red flags around Bountysource too:
"If no Solution is accepted within two years after a Bounty is posted, then the Bounty will be withdrawn and the amount posted for the Bounty will be retained by Bountysource."
"In December, 2017, Bountysource was acquired by a cryptocurrency company called CanYa who redesigned the Bountysource site and service with a new cryptocoin focus."
Edit: It looks like there are red flags around Bountysource too:
https://blog.elementary.io/goodbye-bountysource-hello-github...
"If no Solution is accepted within two years after a Bounty is posted, then the Bounty will be withdrawn and the amount posted for the Bounty will be retained by Bountysource."
"In December, 2017, Bountysource was acquired by a cryptocurrency company called CanYa who redesigned the Bountysource site and service with a new cryptocoin focus."