It depends on what you are studying. In general , I doubt you really need much.
If you decide to do herbalism , get some basic herbs and oils. This is something I don't do so I would suggest you just look at the Herbalism section. If you are not into it, then I would suggest not to bother.
Getting some candles would not hurt. Getting White is a good idea. It can be used for pretty much anything.
If you are interested in utilizing candles , try buying Blue, Yellow , Red , White and Black. Buy some in stick form and some that comes in mini containers. That way , you will have the tools to change the color of candles easily. Yellow and Blue? You get Green. It does not always work and the color may not look the exact shade you want but that's part of the fun of it and you can always keep trying. Different waxes may not mix too well either but it is more an experimental thing. You can keep unused wax in your cheap jars.
When I am in the mood for playing with a smaller fire , I would sometimes play with candles and mixing the colors. When I am in the mood for playing with a smaller fire , I just start mixing candle waxes in an attempt to change it's colors. Of course , it is not neccassary if you just choose to just buy a whole range of colors but I doubt you will need it.
For crystals , I doubt you would need it specifically at the moment but getting Clear Quartz as a generalist stone would not hurt either.
For elemental representations , you can fill transparent empty glass jars with burnt ashes , some dirt , some water etc. Since you live in a forested area , it should not be a problem.
I cannot really think of something that you will truly need. Even those that you mentioned , unless you are specifically studying a topic that demands it , you do not really need it either. At most , get a bunch of white candles and clear quartz and you are pretty much set. The rest I am sure you can easily find substitutes.