As far as I know, there are only two soul gem bags available in the game and both are exclusive: "small soul bag" and "medium soul bag" (the latter being only available from Marraenoloth in the Shroud).

Unfortunately, with new monsters and so new types of soul gems, I now have more types of soul gems than there is room for in these two bags.

So I would suggest one or more of the following:
  • Make large (or larger) soul bags available in game.
  • Make large (or larger) soul bags available in the DDO store.
  • Remove the "exclusive" property from small and/or medium soul bags.
  • Merge the weak, standard, and strong variations of each type of soul gem.