For the longest time, I lived close to a cabinet mill. They would regularly set out in the corner of their parking lot end cuts of maple, oak, cherry, hickory and cedar. All you had to do was beat savengers looking for fire wood. In my first 150 guitars, about 3/4 of the neck wood and fretboard wood came from this stack. Look for a cabinet maker, tell him what you're looking for. You can often get wood for free or cheap. If you have a good table saw, think about repurposing wooden pallets. Many are made for local hardwoods. I have found a lot of oak and once even mahogany. Finally, repurpose furniture. I once found the equivalent of 15 necks in a kingsize mahogany headboard that I bot of $20...
just some thoughts.
I have a local cabinet shop that has a burn pile ,, believe it !,, as stated above took and left one of my guitars ,, from then on has been "Help ur greedy self " This is a cabinet shop ,, all the scraps are high grade .. lengths as much as 10 to 12 feet .. I table saw em down to 1.5 ,, some ,, if the pattern is interesting ,, I'll stand on edge and get me fretboards ,, plane em just a scode and u good to go !
I'm fortunate enough to live in a small community that has a number of cabinet shops. Twice I have approached different shops asking for a few pieces and been sent home with a truck load! Both of these shops were delighted to have someone haul off the scrap.
Be careful what kind of wood you use. https://www.youtube.com/watch?v=JExaZHOfxfY