Here's my tip:
To transmogrify gear, you need to have the source armor in your bags. What are some of people's favorite sets that can be obtained outside of raiding, and are not BoP?
1. Pieces of the Defias Leather set: Rogues love it!
2. The Black Mageweave set, especially on female toons. I don't care to comment on people's aesthetic sensibilities, there are going to be people who would like their toons to look slutty.
3. The imperial plate set - this model is very close to the stormwind guards armor.
Farm these drops, craft a couple of sets, get mats for a few more. These will make a nice profit in a small niche market once the patch hits.