I have only bought the boneless Costco butts before this last time. Safeway had them bone in for $.79 so I picked up three at that time. Costco's are just cryovac'd, no netting on them.
I have never tied the boneless ones before. I just kind of place them on the grate upright so they don't open up or fall over, and did this with them when I made the buckboard bacon as well.
I haven't checked the prices at Costco recently. I have bought a full packer brisket there once, can't remember the price, and had to specifically ask for it as they don't put them out. I used to buy the boneless butts at $1.39 a pound, which are preferred for the buckboard, but I really liked the way the bone in this time cooked. It took the same amount of time for me, 14 hours at around 240 consistently. I took it off at 190, foiled and let sit in the cooler for 5 hours. Had a lunch date that day.
Usually prices at Costco fluctuate depending on so many different variables. I'm sure one of them is popularity. But I have noticed that you can usually get things cheaper elsewhere when they go on sale. I check the ads every Wednesday and save them for the week, and haven't noticed a difference in quality from Safeway's to Costco's.
I did notice at Wal Mart one time that their pork is tremendously enhanced. The tenderloin was at a 12% solution which to me is huge. The butts were at 8%. Needless to say, I'd rather pay a little more for unenhanced meat if I can get it.