About the 1.12.1 version, I just saw that the prices are going to change.
It is supposed to be cheaper but I didn't really understand how it will work exactly.
I just know that you'll need a skill to ride your mount:
75 at level 40 and 150 at level 60.
Paladins and Warlocks will receive the appropriate level of riding skill when they finish their quests.
When patch 1.12.1 goes live all characters who have a mount in their possession will receive the appropriate level of skill to ride it. If you have the riding skill but no mount, you will receive apprentice riding.
All mounts will now be bind on pickup, and purchasing non-racial mounts will require an appropriate level of faction.
The PVP mount requires skill 75, but players who currently have the mount will be given Journeyman (150) riding skill when the patch goes live.
The AV mount requires skill 150, and players who have the mount will be given Journeyman(150) riding skill when the patch goes live.
About the prices I saw that:
skill normal mount : 90po
skill epique mount: 900po
normal mount : 10po
epique mount : 100po
The main purpose is apparently to give you the possibility to buy a mount from the other races cheaper...