I just tried this today and i searched the forums but couldn't find any posts about it.
So for this you need to already have around 250 gold and 375 shadow weave tailoring. What you are making is a ebon shadow bag. First go buy 4 shadow cloths(around 40each) from ah and 4 netherwebs(around 5g each). Then 1 primal fire (around 20-30g), primal shadow (10g), and imbued netherweave bolt(8-10g). Go to the altar of shadows (in smv) and make your shadowcloth (should get 2 for the mats of one). Then with your 6 shadowcloth and 4 netherweb you can make a ebon shadow bag.
On most servers I have seen they are not common on ah so you can nudge the price a lot. I sold mine for 400g and i only spent roughly 220g on mats. GL
EDIT: Meant to put Make a quick 100-200g with 375 tailoring