I like the bit where she (and I am confidently assuming the seller is a she) underlined the word trilogy, because obviously western literature has a great tradition of trilogies and as part of that tradition, it makes sense that we would drop twenty clams on her used books.
I can understand why someone would read 50 Shades of Grey because their friend lends it to them, and they figure they might as well see what all the fuss is about.
But reading all three? And thinking well enough of them that you can only sell them as a unit?
What kind of a sick fuck would do that?