> Amazon was 40% less than list for books -- which was a massive amount, even if you lived in Barnes & Noble markets (and B&N wasn't as pervasive in 1996/1997 as your average mall bookstore was), where there were similar markdowns.

This.

But even for pure list, Amazon didn't pay sales tax so had a 5-8% advantage.

Amazon killed all the technical bookstores in short order because of that pricing advantage that they didn't deserve.