Now I calculated this with an Excel spreadsheet.
For me it does as follows:
100 stacks of herbs -> 500 Ink -> 166 Shoulder Enchants -> 3124,8g Profit by selling it to a vendor
Within my calc, if the stack of herb sells on AH for less than 32,89g this method returns plain monetary benefit.
Not considering the opportunity costs and the Starlight Ink procs.