Get count of items in iBooks
If you are looking at the iBooks "All Books" and you Select All and then, with everything still selected you click on one book and keep the mouse button down and then drag just a tiny bit, as if you were going to move the books somewhere--- if you do all that, you will see a little red circle with the number of selected items in it, attached to your cursor. See the picture. The purple arrow is pointing to the red circle with (in this case) "90" in it.

You do have to move the books a little bit but you don't have to move them far for the selected count to show up.