Faction Reputation Discounts for Flying Mounts

I was doing some research and trying to find out which WotLK patch introduced discounts to flying costs based on faction reputation. I am Honored with the Kirin Tor (lvl 80 Night Elf) and with Honor Hold in Outland. However, at Honor Hold, the cost for epic flying is 4.5k. Hira Snowdawn in Dalaran, however, the cost for epic flying is still 5k, and cold weather is 1k. Does anyone know at what point the discounts come into effect for the Kirin Tor, or am I doing something incorrectly?

For reputation discount about flying skill you need to look for Trainer located in Hellfire and Borean tundra

Hellfire = Stormwind/Orgrimmar reputation
Borean tundra = Valiance Expedition (Alliance)/Warsong Offensive (Horde) reputation

for the lower cost you need to reach exalted (it will cost 4k gold)