I came across this thread after adding a couple of books to my shopping cart at Bookdepository. I hadn't checked out yet, so I clicked on the provided link and added those same two books to my cart without being logged in. I found that both of them were now priced higher than they were previously. There was over $7 difference in price for those two books, with one being $5 more. What gives with that?
I appreciate the link but in this case you might want to double check the prices before assuming that 10% off is a good deal.