From a logistics standpoint, and considering I don't have BfA yet so I don't know how @120 will work, my experience has been that it's FAR easier to gang up the same profession e.g. Tailoring on the whole group and figure out what sells well from those guys. Then sell those things and just buy what I can of the rest once money isn't an issue. Granted, won't help with things that are BoP only, but for things that can be traded between toons, it makes things a LOT easier moving inventory around to the guild bank and such.