I’m not a costco member, but that looks like typical flats you can get anywhere else and right now for cheaper. It’s on sale at Aldi and Amazon fresh for $2.99 /lb and at Ralphs for $3.99 /lb. The BEST deal is at Smart and Final, with their digital coupon it’s $1.99 /lb
I will say, that some Costcos do have Snake River Farms corned beef.