From what I understand (I'm not positive), all the birds that go to the Grand, come directly from the factory. But, they pay a dealer with the markup, so the dealer gets the money without having to handle the actual birds. As far as who supplies Sparta, I don't know.
I believe White Flyer's prefered method is for you to make an order thru your local dealer, White Flyer then likes to deliver the targets with their trucks (be prepared for palet deposit). The dealer never sees the targets, just handles the paper.
Contact Phil Murray, National Sales Rep, in Houston at Regent Chemical (owner of White Flyer), for your local dealers.