Money for Kills plugin

I am looking for a simple plugin- its called Money for Kills or something.

I know there are other plugins out there that give you money for kills, but what I'm looking for is this:

Prevent players from killing their friends over and over for free money!

The config:

money gain per kill:
percentage decrease per kill on same player:
time of not killing that player before percentage reset:
amount of kills before percentage decrease begins (this is getting complicated, but its a nice idea)

Pretty much the more you kill a player in a certain amount of time, their value of money goes down by a percentage to prevent you from farming off one person (they may be afk, they may be your friend, no spawn camping, etc).

However, not killing that player for a set amount of time resets them back to normal value.

I just realized, Even easier, you could do this!:

money per player kill:
amount of kills on one player before no value:
amount of time before reset:

This makes things way less complicated. After killing a player a set amount of time, their worth nothing until the reset.