Yes, to these. Math for us was just under $200 a year, and probably close to that for biology and chemistry with labs. We were able to borrow a very nice microscope, and I did lots of bargain shopping on other subjects, used the library for lit and most of history, etc. Our cheapest year by far was his senior year. He was dual-enrolled for several electives and Spanish 1 & 2. $58 to the school plus a flash drive. Can't beat that! The two classes he took at home were cheap too- borrowed for one, bought used for a great price for the other. ETA: Grades 9-11 were more expensive than I'm spending now on the youngest, but he's only 7. I guess we'll see how that works out.
I think costs also depends on teaching/learning styles, what can be found used (or if you even buy used), and if more than one child can use the same books over again. My friend with 7 doesn't bat an eye at the price of high school math because she knows 6 more kids will be using it for free.