Wotlk flying was not supposed to be bought if you checked its Beta/Alpha. There was a questline that was going to involve flying combat, but that didn't turn out well. New pathfinder achievements should have reputation and questing removed, and add a unique questline (that isn't cheese-easy like everything nowadays) for flight.
Flight wasn't cheap in Wrath and TBC either. Adjusted it would cost around 100-500k gold today.