Originally Posted by
A1m
Buy the Cenarion War Hippogryph but dont learn it. This is enough for the Cenarion War Hippogryph Achievement. Then talk to a GM and say that you didn't wanted to buy that item. At this point you keep your Achievement, this is the first exploit.
The second part isn't working everytime:
He will restore your Mount and give you the gold for the item, since the item costs 2000g, but you get it for 1600g because you are exalted, you get an extra 400g!
This worked for me, but not for 2 of my friends, they got only 1600g. For such an expensive items, most GMs look what they do. If you buy Items for around ~100g while you are exalted with that faction and then let it restore by GMs, they will almost ever give you the full price.
Last part is only theory.
The GM will order you to delete the Hippogryph. At this point don't destroy it, but learn it. The GM will check your Bag for that item and you won't have it, since it is a spell then.
I don't wanted to risk 1600g, so I didn't tryed that, but the first two parts are definitive working. :-)
mfg A1m