Most of the small mills (small kiln and a portable mill out behind the barn) I've delt with are lucky to know about the grading system, let alone use it. These guys I get the best "deals" from. More due to the way the prefer to do business than their lack of knowledge. Its unlikely that I could go and pick up 100bf of premium walnut at a time from these guys. Usually 20-25bf isn't problem. If its 100bf of premium I need, I fully expect to pay a premium. Around here, walnut is readily available, but still demands top dollar for the good stuff. Buying a substantial quantity of premium wood at a premium price sight unseen is not something I'd be willing to do...
The best by far, by the bf deals i've come across have come from Craig's list. Often few and far between, but well worth the wait.
"..... limited only by imagination"
"Just smile and wave boys, smile and wave"
Skipper the Penguin