Buy on Gumroad.
Sorted into easy to access categories:
Art - Brick - Stone - Wood - Metal - Grunge - Misc - Ground - Paper - Glass
I've also added in some uncategorised materials from older packs, with over 200 bonus materials as well as the 500 custom made for this pack! These bonus materials are ones I've used personally over the last year or so, and are not named or categorised (the 500+ pack ones are though!).