Yay, a new tip that I have yet to see on any forums/blogs.
Engineers can craft , which at first appears to be "A random bundle of fireworks!" However, when opened up, these fireworks have a good chance at containing one of the following schematics.
Now to give you an idea of how unknown these things are, at the time of this post, there were less than 10 of each across all horde US realms. It's probably not something I'd advertise in trade chat, but try posting them on your realm for a decent price and see what happens.
Important: Do not learn the schematics! Once you do, you will no longer receive them!