I was at Costco yesterday and found they had 3 packages of USDA Prime Brisket for $3.79/lb sitting right next to their USDA Choice which was $6.79/lb (or something, obviously didn't buy that).
Definitely YMMV. I'm smoking the 11 lb brisket now and it is nearly ready to eat. Looks like a really good piece of meat. I'm definitely no expert though.
I'd love to hear people's feedback on this. It is my first post, and one I felt worthy of sharing. I'm sure prices like these are very regional (and I did leave one in the cooler for those nearby).