Upon leveling my inscription i saw i needed Deathwing Scale Fragments, and to cut a long story short, i've found they are selling from vendors in Twilight highlands for 4g 80s each, and selling on the AH for 90g per.
Una Kobuna in Dragonmaw Port sells it for the Horde
Casandra Downs in Highbank sells it for the Alliance
Same with the other inscription items that used to be rare vendor spawns (but appear not to be anymore) however these cost a bit more (13-35g) and sell for the same amount of gold on the AH. (Of course this all really depends on your server)
So yeah it may not be the biggest money making scheme in the world (of Warcraft) but it is a handy little thing to do as a side line money maker