Also, if a given player is becomming too powerful, he can just buy his way out of the problem, and that, i think thats a bad idea.
I have to agree there, of though I still think lowering bounties to an extent might still be a good idea, but I do agree, that once you have the funds you can clear the bounty quite easy yourself, but maybe once you have reached X amount of wealth, the price of clearing the bounty increases?
0 - 1000 no extra charge on top, that is if you have a bounty of 1000 you can pay 1000 to pay it off
1001 - 10000 you have to pay 25% extra so that a bounty that is 12500 should cost you,
and so on, but this is just rough figures, so the more you own the more expensive it is to pay off your bounty, so its more difficult for rich players to pay it off completely