My original MX Master just crapped out on me after 3 years of daily use so I went looking for it's replacement...the infamous sequel MX Master 2S.
I was about to settle on Amazon who has it for $79.19, but decided to check Staples first and lo and behold their $25 off $75 code (90011) worked on this mouse. So it was $99.99-25=$74.99 plus tax with free shipping. Tax was also less for me in Illinois with Staples at 6.25% whereas Amazon is 10.25% (Sidebar: Why?) Without further ado:
Coupon Code: 90011
NOTE: Coupon appears to be a member exclusive "Offer valid only for select customers."