Vlad, you answered your own question without realizing it - there is no limit to the number of times you can bounty a player! As far as the limit to attacks in one day, this is probably due to all the inactives people were attacking just to clean out their cash and Admin very likely found a way to curtail people's greed.
If someone is truly bountying you in this fashion that is exactly what you should be doing in return...BUT: wait until the player is logged on (it means so much more when an online player is forced offline!).
If there is one person harrassing you like this it tells me both of you are not in a clan or in a "clan of one." Why don't you PM me and let me know this player's name? One or two of my clan members had branched into their own clans and were assaulted in this same manner. Could be the same player or his associates (also in no clan). PM me the name of the person and I will try to assist you also. Please don't quit; I've seen you logged on and you're a nice, quiet person. My clan helps many nice individuals without requiring them to join us