I advise joining any group killing the rabbit that is allowing everyone to need on this pet ^^
Only one of these drops per kill so be prepared to lose out on it a lot before winning, also by killing the rabbit you get That Rabbit's Dynamite! worth killing it at least once, even if you did end up buying the rabbit from the AH.
Seeing how this is a 20+ person raid (unless you have a guild group), good luck not having an open roll group. The times I have seen it done, coordination is pretty key as the rabbit does like to jump around a kill people. We were lucky one time to get it suck at the entrance and ranged was able to get about 60% of it's health down before someone got too close and it went on a stomping fury again. With the rarity of it to begin with, AH pricing would be very high.