*This is called wild speculation. I'm fluent in it. Get @ me.
That being said, we'll be selling them until Mists launches. The following is a pricing list for each instance.
Heroic Rag Mount - 75k, includes any gear that drops, but if you need gear for anything other than Transmog from FL, consider yourself fortunate you have gold, because that's just sad. If you do not already have the title, there is an additional 25k charge.
Heroic DW Mount and 8/8HM clear - 50k, includes any gear from the first 7 bosses that drops that we don't currently need(i.e. those random trinkets that can drop off most bosses, but never do). Prot and Conq tokens in particular, tend to rot. 25k for Madness drops if interested, and an additional 25k if you do not already have the title.
For more details or to reserve a spot, pst Oneiro in game.