[Rob]

all you have to do is make it where you cant turn in more than 1 head per day or something =p

You could always do it like counter-strike:

If you kill someone, 1,000 gold is added to your head. Whoever kills you gets the gold. You'd have to award it to the killer's bank though, because someone else could steal the head, or just allow that to happen as well hehe. When the person dies, their bounty is cleared.
If needed you could put a cap on the amount of bounty that is able to be added per hour or day, such as 1 kill (1,000g) can only be added once per hour max (something along these lines)

I think it would be easy for someone like Taran to detect abuse of this =p

Then that would be exploitable. The confusion with Habibi Jones was that he thought the system was injecting gold into the world vs the bounties coming from the player's bank accounts.