I enjoy mix books but have been dismayed by how much their prices have risen in recent years. I've been looking for a better curriculum and haven't found one, but your books are simply getting so expensive today, even with the 50% discount. I used to be able to afford them, but now I can't justify the cost. Aside from the price, I adore the books in every way. My last several volumes have had to be paperbacks rather than hardbounds, and they are still rather expensive. That is why I gave it four instead of five stars.