I like the primes at Costco, but they're not always in stock at the one I go to. Huntington is great but pricey. They have all kinds of good stuff there and the folks are really cool, plus one of the best apple fritters there are can be found at Bob's Donuts right by there. As mentioned, Marconda's could set you up as well.
Not sure if a place like Bristol Farms would have packers in stock, but you could probably order through them. It will def. be very expensive, but they carry SRF. Handy's in Burbank might have something like that - maybe not in stock, but pretty sure you could order through them as well. Very good stuff there.
Harmony Farms in La Crescenta is a cool spot - not sure if they carry packers, but they have a lot more options than the average butcher.