I thought so-called "cooking sherry" had salt added to it on purpose to discourage people from drinking it --- well, maybe not exactly that; I suppose the salt was considered a useful flavoring additive.
My mom kept an inexpensive sherry such as Taylor's on hand for cooking, and I do too. She didn't drink sherry straight, and neither do I. Sherry is a great addition to many creamy and brown sauces and soups, and it only takes a bit to get its effect. Marsala and white vermouth are too, for different flavors.
Bottom line for me, Taylor's sherry and marsala for about $7/bottle are fine for cooking. If beyond that you like to drink sherry straight, then spend some more.
"Your swimming suit matches your eyes, you hold your nose before diving, loving you has made me bananas!"