The bounty system works simple as that:
If you are going to place a bet in someone ( Just putting a bet without a text ) it would cost from 100tc to the amount that you think that'll be necesary, this is like for friends and those kinda of things.
But if you want to put a text under your nickname in-game you must pay 2000tc and another 100.
Here you can see:
Victim:
Amount: + 2000 TC base price!
Bounty Text:
In the first part just put the name of the person
the second part the amount
and then the text that you wish to be write.
For more information I suggest you to go here:
http://forum.toribash.com/tori_bounty.php
then you'll see how does the system work.