I personally don't worry about coupons, I worry about how sites can use data about me to dynamically adjust prices to "what I'll pay", instead of giving the same price to everybody. From my understanding sites like Amazon have even been caught doing these practices before. And we already know places like Airline companies do this.

The problem is when sites like Amazon require accounts, there is not much to do to get around being tracked and having dynamic pricing come into play. At least with airlines you can VPN and use private browsing to try and avoid this practice.