This thread allows the compilation of a very useful sellers list which can be used as a reference for decades to come
Besides, neither the other thread nor this one give a definite answer regarding whether the "starter" is needed.
I don't find clear answers on APUG.
Some people say that the "starter" only has the purpose of making the "replenisher" less potent during the first runs. That would mean that the "replenisher" alone could be used, maybe after having tweaked the development times.
But you can also find different suggestions. PE - talking IIRC about C-41, not E-6 specifically - says it is adviceable to use a developer which doesn't require a starter.
A Kodak document says that for rotative processing the Kodak "kit" should be used (107 7643) and not the starter-replenisher one.
I cannot find the product code of the first developer of the Kodak kit. Could be 156 4632 but Kodak documentation is ambiguous on the point. It says the kit 107 7643 "replaces" the various products with various codes, among which the first developer is 156 4632, but it is not clear if it replaces them because there has been a change in formalin content, because there has been a change in packaging, or a change in formulation.
So far the only seller I was pointed at who would sell E-6 components is Morco Photographic Products, but they don't ship E-6 products overseas.
I think I'll have to buy an entire new kit