Don't bother. Most of the demand is the new skin, the new cloth, the new flowers, the new things. Not the old things. Some people say, the bags, the this the that, but those even if they have some demand, will be exploited so much that it won't be easy to shift products fast enough. Besides, if something "profitable" is public, it won't be profitable for long.
i.e. Cue 10,000 stacks of embersilk cloth on the AH "but why don't they sell?". Because 1) 100s of others thought the same 2) People actually need the new cloth more 3) Some guilds and people that didn't even care to stockpile get rid of it.