I did some digging on this to try and find concrete evidence and most of the sources arent.
However, it seems as though initially the vendors in Grobb and Oggok didnt sell the correct supplies either, and it was fixed:
http://www.project1999.org/forums/showthread.php?t=561
there are links in this thread that state Cabilis should also sell the ingredients for SoW potion, ect.
Lists Cabilis as selling the same ingredients.