If you haven't done so already, go do Obsidian Sanctum on 10 man and leave all three of the drakes up. With Patch 5.1 you can enter old raid instances without having to form a raid. Saratharion should be soloable by most classes at 90. He always drops a 22 slot bag, and with 3 drakes up he'll drop Reins of the Black Drake. If you're really feeling adventurous, grab 1-3 more ppl and try the 25 man version. He drops Reins of the Twilight Drake.