I might have a slightly different approach then some here,
and i teach traditional pottery making the same way....
so for what its worth here it comes
<<<DON'T SPEND MONEY>>> ALWAYS start with what you have.
What grows around you? study up and get familiar and knowledgeable with all your trees, bushes, grasses (and even domestic varieties)
internet as well! My Wyandot ancestors in Ohio were not "primitivists"..they just knew what was around them and made things
from what they could find and/or trade for.
what tools do you already have? because with those tools... there are alot of other tools you can make.
what can you find by scrounging? dog chew-bones can be cracked and made into some fine points.
a temporary string might even be made from using bailing twine fiber. experiment, and hang weights on your strings to see how tough they are.
I agree with sleek...forget about buying a board.. you don't know where that board came from .
cut a 8" dia. straight sapling of hickory or hackberry in about a month, when the buds start popping, quarter it
and peel the bark. look what you have in your garage (get some ol paint or ol varnish) and coat the ends and the back sides
throw em up in the rafters of an outbuilding and let em bake all summer. In the meantime read up,study the back posts of Primitive Archer
work on making cordage from ALL KINDS of stuff... and cut shoots for arrows ,look around the woods or neighborhood now when the leaves are gone.
wild rose is almost everywhere, red osier, and other shoots can be tried. seal the ends and bundle em. for a couple months
till you can scrape the bark without them splitting on you. start collecting turkey feathers...
but anyway...thats the best way to start in my opinion.
start with what you got