This all comes down to economics. Big raw material suppliers do not want to sell small quantities. So, they have high minimum order quantities. There are a number of “repackers” like https://makingcosmetics.com
The problem is that they have to buy a large quantity, then hope that they get enough small buyers to get their initial investment back. It can be done but it seems like it’s a tough business to be in.
Imagine, you have to put money upfront to buy your raw materials. The more diversity of your selection, the more money you’ll need to have tied up in inventory.
Then you have to split up the bulk raw material you bought (55 gallon drum or a 50 lb bag) into smaller units.
Then you have to sell each of those units. This involves packing up the containers, shipping to some address, including the proper paperwork, then having customer service to handle complaints/returns.
These businesses don’t really want to be in the commodities business selling popular ingredients because then it just becomes a price war to get to the lowest price/profit.
So, they want to be the exclusive seller of a hard-to-get material. That way they can maximize profit while minimizing competition.
But some ingredients big companies won’t even sell to small distributors. There is just too much hassle for not enough profit.