Actually, I think that losing money upon death is a really interesting concept if designed appropriately.
In United States there's the concept of health insurance. Considering that there's big amount of people against forced CK, we could introduce the concept of health insurances.
The insurance can be used in multiple scenarios:
Pharmacy Drugs
Depending on the health insurance's premium, you could pay discounted drugs, heavily discounted, or even for free.
Brutally Wounded
Anytime a player will visit the hospital because of whatever reason, let's say a player has been brutally wounded, but the Fire Department manages to save them, or somebody goes on their own to heal themselves.
medical expenses should be calculated based on the Injuries Cost Algorithm (ICA) and paid directly from the character's bank account upon "being healed";
If the player is able to pay the medical expenses, the player will be immediatly respawned like usual.
If the player does not have any health insurance, or the insurance is expired, or the player does not have enough money to pay the medical expenses, the player will be placed on a cooldown 50% lower than the player kill cooldown, based on the health insurance premium.
Player Kill
medical expenses should be calculated based on Injuries Cost Algorithm (ICA) and paid directly from the character's bank account upon death;
a temporary cooldown will be placed on the character based on the premium of the character's health insurance.
If you not enough money is available in the bank account, the player kill temporary cooldown will be duplicated.
The cooldown works like a temporary timed ban and should automatically be lifted once the set time has passed.
The player will not be able to login with that character for this amount of time.
The cooldown can be lifted by an administrator in case the situation has been voided.
Health Insurance Premiums (examples)
The cost scales up drammatically based on the quality of the premium, to ensure that people will need to pay hefty amounts to have their cooldowns drastically reduced, therefore discouraging players to die or make shootouts for no reason.
No Insurance (default)
Cost: free
Deductible: none
Medical Expenses discount (post-deductible): 0%
Pharmacy Drugs discount: 0%
Bronze
Cost: $150/week
Deductible: $2,000 (meaning that you always pay the first $2,000 in a week of medical expenses)
Medical Expenses discount (post-deductible): 40%
Pharmacy Drugs discount: 30%
Silver
Cost: $400/week
Deductible: $1,000
Medical Expenses discount (post-deductible): 60%
Pharmacy Drugs discount: 50%
Gold
Cost: $950/week
Deductible: $500
Medical Expenses discount (post-deductible): 80%
Pharmacy Drugs discount: 70%
Platinum
Cost: $1300/week
Deductible: $0
Medical Expenses discount (post-deductible): 90%
Pharmacy Drugs discount: 90%
Player Kill Character Cooldown
Player Kill Character Cooldown is composed by a 1 hour + 15 minutes minutes every level in-game with that character. This discourages in the long-run deathmatch, but at the same time it's more lenient towards newer players.
For example:
Foo Doe is a level 5 player. His cooldown will be of 2 hours and 15 minutes;
John Doe is a level 12 player. His cooldown will be of 3 hours and 30 minutes,
Marko Polo is a level 25 player. His cooldown will be of 7 hours and 15 minutes.
Players under level three will have a static cooldown of 1 hour.
Injuries Cost Algorithm (ICA)
For example, if you have been shot in the head, the medical expenses will be higher, compared if you were just beaten up to death. A proper algorithm should be designed in order for this to work)
If you do not have health insurance, the PK will always place a cooldown on the died character of 60 minutes.
These are just some ideas that I have, of course they are not perfect but it could be an interesting approach to investigate further.