Im going to give you guys a list of easy rare mounts you can get. All of these are soloable at 85
1. Raven Lord (http://www.wowhead.com/item=32768)
This mount drops off the boss Anzu. He is the second boss in Sethekk Halls (Herioc).
You can run normal dungeons until you can enter herioc (you have to be honerered)
You can only do this once a day buts its very easy.
2. Deathcharger's Reins(http://www.wowhead.com/item=13335)
This mount drops off the last boss in Stratholme.
The guys a 51 elite and incredibly easy.
You can do this as many times as you want however, a typical run only takes about 10 minutes
You can only do 5 runs an hour.
3. Swift White Hawkstrider(http://www.wowhead.com/item=35513/swift-white-hawkstrider)
This mount drops off the last boss in Magister's Terrace on Herioc.
This one is a bit harder but still doable for any 85.
You have to do this dungeon on normal once to unlock it.
You can do this once a day.
4. Fiery Warhorse's Reins(http://www.wowhead.com/item=30480)
This drops off the very first boss in Karazhan.
I soloed this boss on my full green 85 rogue so anyone should be able to do it.
You can only do this once a week so its quite rare