Sources for fine grained cabinet wood?

[Robert Williams]

For those of us who have the chance from time to time to repair/replace
cabinets on synths like the Minimoog, how might a person find this fine
grained wood?  I've never purchased fine wood like walnut or maple
independently - all the nicer wood I've ever worked with was in college
woodsmithing class where it was provided as part of the course.  I know my
local lumber yard does not carry this stuff, so is it difficult to obtain?

Basically, my question is where do craftsmen of homemade electric guitars or
gun stocks find this better quality wood?  Would a local cabinet maker know?

Robert