No, you can only freeze them when they're not on sale. (It's a joke, dear one. It's just like when a waitress says, "My name is Betty if you need anything," and you wonder what her name is if you don't need anything. Oh never mind, for heaven's sake!)

Actually, both whole milk and sour cream suffer from visits to the freezer. They separate and are impossible to put back together again. If you are planning on using them for cooking, then fine, you won't notice that they were frozen. If you're going to drink the milk or use the sour cream on your taco, then no, don't freeze them – you'll notice a difference.