If you need cheap bags for some reason, ZA has 20slot bags for each player from the quest, mag has a 22 bag per run, ZA has the gnome trinkets (if your running all shaman, the gnomes spamming chain lightning is pretty funny imho) and loads of cash, the eye has the nice shoulders for priest/warlock ihmo as well, os has the mount obviously. You should be able to do os10 with help from a friend at 85. Getting lucky with positioning and learning the zerg strategy is likely the hardest part since other than that its really just target dummy for the dps as there is no time for a position move.

Onyxia also drops 22 lots bags, lol ... and chance at a mount in 10 or 25man. This should be pretty trivial for two teams to farm once they get a rhythm going for the whelps and dealing with her flight movement.