You must have RotHC, right? I say that since, IIRC, 28's are level 53. I don't have it, so the highest I can use it 27. I would very much like to outfit all my custom gear with specific advanced 27's.
That's why I'm curious if you can actually learn the green 27, and then RE to purple, or if you have to extract the purple from Dread Guard and RE that. I suppose I'll find out once I hit 400 in Artifice and Cybertech. Of course, then there's the issue of finding the mats to make them D:
The only mat that actually seems to give me trouble is molecular stabilizers. I'm gonna need 120 of them to make all the mods on my main toon wishlist, and I've only seen 3 of them on GTN, each for 100k creds!
I may wind up having to settle for Advanced 22/25 mods or some such. :/