Mazmart has mnay parts...usually pricey.
Papa Joe is a great guy, he does have some parts.
I have a boatload of Miata parts...mostly NA stuff but a few NB things as well.
What parts are you searching for?
Ya man all the Spec miata guys snag the decent stuff, sell the bits and pieces for top dollar, and turn the chassis into a racecar. Good luck finding Miata parts in a yard, so far I have only seen three ever.