Currently the only way to mechanically place contracts on people is through the assassin's guild. Logically the assassin's guild isn't an organisation everyone wants to use.
In many medieval and fantasy settings bounties set by local guard forces in cities and towns are very common. On Arelith we already do this by allowing people to turn in heads of NPCs, but the only way to get rid of a pesky criminal at the moment would be either to try and have your own Guards kill / remove them or call in the evil assassin's guild.
I feel like a Bounty Hunter guild could really add to the server and allow for Settlement Guard forces / authorities to issue bounties on player characters not for use of getting rid of someone you simply dislike or to overthrow a government, but to handle local criminals. I understand this is not an easy system to create as it would be prone to abuse if not well thought out.
Some rough ideas may be to introduce an option through the settlement menu to settlement leaders and others through set permissions much like you'd set permissions to evict/Pariah/Exile where you can list someone along with a gold bounty that would be paid out of the Treasury when someone hands in the ear of a bounty (or maybe some token that is created and falls from their corpse so we don't encourage corpse bashing maybe? (min. 100K like the assassin's guild.)
A board like the Pariah Board or maybe just a cool wanted poster in the city could then list out bounties to deal with local criminals. When 1 person delivers the token or ear to collect the bounty, the bounty then disappears.
Again, I get this might be prone to abuse but I don't think it would be more prone to it than Pariah/Exile/Eviction if it's managed by settlement leaders and with some rules and guidelines around it. But it just provides an alternative for settlements to deal with local criminals without the need to hire other criminals.