What you are actually selling
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The material is rarely unique
Mica, fragrance oil, soap base and wick are bought from a small number of upstream producers. Two suppliers selling the same mica are selling the same mica.
So the differentiation is elsewhere
Accurate identification, a usable quantity, a container that works at a bench, consistency between orders, and information the customer cannot easily get.
Identification first
Which colorant, by name, with its regulatory status and restrictions. "Purple mica" is a marketing name. The additive it contains and what that additive is approved for is the fact.
Consistency is what keeps a customer
A soap maker who has matched a colour across three batches cannot tolerate a fourth that differs. Lot-to-lot consistency, or at least honest lot marking, is worth more than price here.
Quantity matters more than in most crafts
A hobby maker wants 10 g of a mica, not 500. A production maker wants the opposite. The same product in three sizes is three products commercially and one product operationally.
The container is part of the usability
A powder that cannot be dispensed without clouding a workspace is a worse product than the same powder with a sifter. The shelf has 13 spice caps and that is the difference.
And information is the cheapest thing you sell
Usage rates, what it does in cold process versus melt and pour, whether it discolours, how it behaves in a candle. Writing that once serves every customer who ever buys it.
Which is the whole argument for a supply business
The margin is not in the material. It is in making a confusing purchase into a confident one, repeatedly, for people who will come back every month.
Decanting is a manufacturing process
Even though nothing is made. The fill, the lot, the label and the seal are the production steps, and the quality of a supply business is entirely in how consistently those four are done.
Which means the records are the asset
What came in, from whom, with what documentation, and which of your lots it became. That file is what lets you answer a customer question two years later, and it is the thing a competitor cannot copy.