Systems for bounty hunting have been proposed before and to my knowledge all of them have been denied, and for very good reasons. I appreciate the sentiment of your suggestion but there are too many ways in which this can go wrong.
As it stands, you can 'sort of' engage in HitmanRP but it does come with severe limitations. If someone pays you to kill another player, you need to establish and be satisfied that there is a good, substantive reason for the killing. In the event it is deemed there was not a good reason, it is the hitman who receives the punishment as he acted in the form of a proxy. This is why it is almost always not recommended to engage in this activity unless you can be absolutely certain there is a good reason.
There are a number of issues I can foresee with your implementation:
Let people pay other players 10k too do some off their dirty work for them after a raid they pay someone too kill someone raiding them as back up.
While I am sure it is not what you intended when you made the suggestion, this could give rise to breakage of NLR Rules. You can argue that you simply make people unable to place bounties while under NLR, or for a short time thereafter, but this can easily be circumvented by people asking others to place the bounty for them. Another way is to make it so staff approve every bounty request - I would counterargue that the staff have enough to deal with and that this pulls their resourcing away from their legitimate purpose which is to enforce the Rules.
The bounty hunter would show its name for the org that the player bought it for
This is yet another way in which I can foresee massive metagaming potential and could even go as far as to step into the territory of Excessive Negativity; if someone has a bounty placed on them, and they know which organisation it is, it can lead to potential targeting against that organisation. In addition, the bounty hunter may not be a part of the organisation that has issued the bounty and could do numerous actions which could damage the reputation of said organisation ICly.
if they get killed while doing the bounty hunt the person who paid gets 50% of their money back the bounty hunter gets 30%
Becoming a hitman should carry great risk in a number of ways: law enforcement, financial risk, and of course death. As we know the economy in-game is massively inflated and thus an asking price of $10,000 is not that great of a risk especially where the person asking for the bounty gets 50% of their money back. The bounty hunter, seeing as they get 30% at a minimum just for accepting said hit, wont be inclined to take extra care and caution to ensure a clean job whereby they are able to escape.
While much of Paralake and its Laws are modelled off of the US system, Paralake is its own entity in a fictional country (as has been explained by community management before) and thus the laws of any real geographical location have no real bearing on its legal system (a lack of courts, transparent justice, trial by peers etc). In Paralake capital punishment is outlawed and for very good reason. By placing some of the monies from the bounty into the city funds, it is almost as if Paralake condones a civilian killing another human being for a cash reward, which is in the same vein as capital punishment. It unfortunately would not make sense.
I cannot support this suggestion - it gives rise to too many logistical OOC issues, and IC legal issues.