Although it would sound as a great idea, I don't think it is implementable in IH. I mean, let's say you put a bounty on me. I just go and hide myself in a safe province and it's all over.
Furthermore, if you place a bounty on me, it must be for a reason (for example, I attacked you and got a certain ammount of gold from you and you cannot defeat me to get it back. What's the point in paying (aka losing) even more gold to practically gain nothing, besides myself trying to find you again and retaliate?