I'm similarly trying to build up my quiver of essentials. I've been perusing techniques and recipes I'd like to explore more, and have been making a list of ingredients along the way. I'm presently focusing on gels and gums and have been going to the websites of the exact ones they're recommending. For example, TIC gums has a great webpage with a place to order ingredients a la carte. I've found a few other suppliers with generic ingredients, but when something calls for 0.2g of something specific, I'd like to keep things as exact as possible, at least in this stage of my learning.
But to answer your question more specifically, several hours of web perusing haven't found any starter kits that would be as targeted as I'd like. Hopefully some entrepreneur will make that happen or someone will post the link that I couldn't find
