If anyone in Orange County is having trouble finding them, the Costco on Technology in Irvine has consistently had them in the prime beef area. The price this week is $2.69 per pound. And as an added tease, they have also have bulk cryovac prime tri tip for $4.39 per pound (I think each pack contains eight tri tips).
I smoked two briskest this weekend, one was a choice from Smart and Final the other a prime CAB from Costco. Everyone praised the choice brisket when they sampled it, but crowded the kitchen for seconds when they sampled the prime. Clear consensus that the costco brisket was superior.