Like Smokin' says,Sam's will bring out a case for you to pick,and then just price the rest to toss in the case.
No problem.
Most MIM teams buy at LEAST 18 slabs of loinbacks,to find the MINIMUM 6 slabs they must have available.
As to the other,the few large producers are buying up all the smaller cutters,and then they cut to the main corporate standards.
Be careful, about some custom butchers,as they try to be helpful and leave you more of the loin on the rack.
Loinbacks sell for much more than boneless loins,so it pays them to leave much more on the ribs.
Then, you have to trim them down,to get even cooking.
The only thing you can depend on,is the price will go up.