I am partial to Athur Bryant's BBQ sauce from Kansas City: http://www.arthurbryantsbbq.com/index.htm
Whenever I pass through KC, I stock up.
If you have not been to the original Arthur Bryant's place in the old part of KC (1727 Brooklyn Avenue, K.C., MO) and had burnt-ends, you have really missed a treat! It is a perfect BBQ place: not too clean, you get the food at the counter, and the only bread is white bread, but the BBQ brisket is top-notch! Put their brisket on white bread, add their sauce, and it is PERFECT !!