Let me copypaste some wowwiki shit for you:
Patch 1.12.1 (26-Sep-2006): The cost structure and functionality of Riding and Mounts was changed.
Prior to that patch, Riding was an ability rather than a secondary Profession, and had only one rank. Each faction had its own riding skill (tiger riding, horse riding, mechanostrider piloting, ram riding) and the cost was 20Gold, available at level 40. Exalted reputation was required to learn cross-faction riding skill, but mounts were Bind on Use and purchasable by anyone for 80Gold. This meant that characters who were PvP rank 3 or higher could pass on the 10% discount directly to other characters by buying the mount for them. This is no longer possible because all mounts are now Bind on Pickup, and the majority of the cost is built into the riding skill training (which is no longer faction-specific) rather than the cost of the mount.
This doesn't mention the 100% mount cost for some reason, but I'm fairly sure it was 1000 gold before discounts.
Basically, what you needed to save 1k gold for back then wasn't the training, but the mount itself.
So how will we have it on Nostalrius? Pre-1.12 way of cheap riding skill and expensive mounts, or post-1.12 way of expensive skill and cheap mounts? I'd expect the former, but I believe this really needs some clarification.