Everyone knows people love buying pets, and how much gold they will spend on them. At level 475 engineers can make these..
These are Goblin/Gnome engineering pets.
Personal World Destroyer - Item - World of Warcraft
De-Weaponized Mechanical Companion - Spell - World of Warcraft
The other engineer items are being made more frequently so sell for less on the AH after you've crafted them to level up. These pets (even though the mat reqs are high) sell almost instantly and you can make a very good profit from them.
I made two and instantly sold both of them for 1,500g each.
The next couple I make I will be selling for 2-3k.