Buy the cook books at AH only if you like being ripped off.  Let's see...90s from vendor or 3g from some jerk for the expert cookbook.  It's not so hard to fly to Desolace or do a quest. 

Let's see... 1/2 hour getting from SW to the middle of Kalimador....  or 1/2 minute of farming Outlands....  It's soooo much easier to just send my alt the gold. Thank god some jerk on the AH wasted *HIS* time flying all over the place.