Seeing a lot of $25-45 (USD) used price.

Used books are awesome. I have north of 500 books and I doubt more than 50 were purchased new. Only that many because some of my relatives want Christmas and birthday wishlists every year, but won't shop anywhere but Amazon and think it's weird to buy someone a used book as a gift (I'd rather have 2-3x as many books for the same money, but hey, I'm not the one paying, so whatever, I guess).