before transmog the best leveling greens and twink gear were ridiculously expensive because max level players leveling alts could probably afford to buy them.
No one really should ever rely on the AH for leveling gear. Ever since Vanilla, leveling guides have always suggested the AH as a last measure and that even then you could level without (and had a guide with which quests got your class what you wanted, atleast until blizzard streamlined the process in later expansions). All the good guides suggested to skip the AH.