I'll give you the same advice as I was given almost 30 years ago.
"RIVER of WOOD"
Those who know of him, know where this advice came from.
Probably one of the most important pieces of info I was given to start out.
Shaft wood...you can never have enough. If you have the right source, it's better than money in an IRA.
Butt wood...(Exotic woods, exotic figured woods) the list is endless of the different types you should be buying and stock piling. Every spare penny you have or can muster without straining your budget should be invested into woods.
Why? you ask....because just like when I started out on this journey there will be a lot more of the world woods that are put on a CITIES list or that will simply disappear from the commercial list of woods that will either sky rocket the prices or make them next to impossible to acquire.
ie: Brazilian Rosewood was still readily available in the early to late 90s. I stock piled everything I could get my hands on simply because I liked this wood for being what it is. Try to find some now. If you do, get your wallet out!
1.5x1.5x18 Brazilian Tulipwood/Kingwood was so available I used to walk in to one of my suppliers and there would literally be 2 piles on the floor to choose from at $9 a stick. Wish I had nabbed more

1.5x1.5x18 Nicely figured Cocobolo/Bocote used to be 8-10 a stick. If you purchased a dozen or more sticks they would throw in free shipping.
I could on and on but I'm sure you get the point.
Exotic woods will never get any cheaper and guaranteed should you decide to change directions from building you can sell said woods and not take any loss.
Seek wood sources and make it one of the most important journeys in your journey.
If you do, you could be as bad as I have been this last year and get a stocking full of coal something like this!