Our local butcher shop sells hamburger by the package and it seems like a great price. Until my husband weighed one and it's 13oz not 16oz. when you figure price per lb, they were the same as everyone else.
However, DH and I have found using 13oz meat vs 16 oz does not cause any problems.
I have a lot of older recipes that call for using specific size cans, but most work fine using a bit less. I'm not going to buy two 14oz cans of pineapple so I can have 16oz to put in my cake.