Somewhat related, there's a chrome extension called honey that will compare the final price (incl. tax) of all sellers for a product listing and add the best one to your cart. I've saved tons of money in some situations where an alternate seller had no taxes, was cheaper but longer shipping, etc...

It's still frustrating the lengths I have to go to to get a fair deal on Amazon. there's so much anticompetitive behavior (showing their own products first on searches, defaulting to products sold by amazon, hiding competitor listings [search for chromecast]) and they show little interest at changing behavior to make the customer experience better (even on glaring issues like fake reviews / counterfeit products) because there is no competition. I have contributed, been suckered in to the 'Prime' bandwagon, rarely shopping around on price, and often buying 'Amazon's Choice' products, which are almost certainly a sham.

Refreshing to see people on here bucking that trend. I'm trying to commit to the same, hopefully Amazon one day feels pressure to change.