jwhealy,
I discovered the same answer to that question just after I bought the OXA set at Cabin Fever this year. I've found that very few tool sellers carry extra holders for the OXA size. i've only found them available at LMS.
I've settled into making my own tool holders. Though I have purchased 2 extra turning and facing holders from LMS, I have now made 5 holders from 6061 aluminum for things like a DTI, my home made knurler, a spring winding guide, a ball bearing bump true tool, and a spare.
If you have a mill it's fairly easy.
Chuck
