Cabinetry Supply? Better lumberyard?

I want to build some extremely simple cabinets and some built in bookshelves for my apartment, however the lumber selections at the big box stores don’t really have what i’m looking for. I’m looking for MDF (medium density fiberboard) in a variety of board sizes, and preferably some pre-drilled for adjustable shelves. Anybody know of such a place in our neck of the woods?

thanks!