I buy Chef Select at Charcoal Warehouse in Memphis TN - great place and great people. You can buy it by the bag, the pallet or the truck load. They also have lump and wood chunks. I try and make a run up there once a month and stop at Resturant Depot as well. On the way home I stop at the Memphis BBQ Co.
I suggest everyone go by there and help keep them in business - I don't want to lose this source.