Still looking for more reviews on any site where you might have bought one, please.
Update: those discounts didn't last; but maybe they'll be back.
Nov. 9 update – Amazon's and Book Depository's lowest price yet: $62.05.
Jan. 1 update – The publisher has sent an updated code good for 20% off through 2018: [not surprisingly] LYON2018 at checkout at their UK or US site. Amazon's price is only 10% off today.
Jan. 30 update – New low: 30% off at Amazon: $56.36
March 2018 update – New low: 32% off at Amazon: $54.63