Not only are king-sized costlier, you also have to pay attention and buy the correct ones: there are king-size and California king. Perhaps this isn't the problem in New York that it is here on the left coast.

We started with a California king when we first moved in together. That's a longer bed. When we replaced it a few years ago, we went with the other kind of king, which is more square. It gave us more elbow room and, since neither of us is tall, the shorter length gave us more space in front of the bed. The fitted sheets from one definitely don't go on the other! Check carefully when you buy sheets.