Definitely seeing red as RED patch hits...
Mastery Books going for 40m and 60m apiece from the NPC, for level 20 and 30 versions respectively.
More copypasta from the MSEA forums:
Items missing from our RED Shop:
50% Epic Potential Scroll (can be bought 5 times) [45 coins]
Gold Potential Stamp (can be bought 5 times) [45 coins]
Special Additional Potential Stamp (can be bought 3 times) [75 coins]
Will update as more comes along.