Just part of the game. Placing someone on the bounty can be because that person has attacked you many times, is constantly attacking you, or you may just not like the way the person plays. Also if you can not beat the person then by placing on the bounty it allows for others to kill them for you. Also there is the bounty achievement, so that may be a reason to place someone on the bounty. As for the high cost of bounties, that depends on the persons income. So the bounties vary w/ each clan, the price on of bounties for 10 different clans at the same level can be 10 different prices. Also check on the bounty price to see if there has been other bounties placed on the person w/in the last day cause that will drive up the persons bounty price.
I agree OP. It costs way too much money and all they have to do is heal for a few hundred thousand and they are playing again. I only place the bounty so that I can get the achievement. No one ever pisses me off in this game that much. As soon as I get the bounty achievements, I don't plan on doing any more.
i bounty all the time, my rival list are usually the people that like to die alot and there usually 50 levels higher than me, i attack them first to gain xp and then bounty them so they lose the xp they gained when they attacked me