I think we ought to be thinking about things like this from time to time. "Buy local" is becoming "buy in giant warehouse size stores with national distribution networks." As smaller businesses disappear and what's considered a small business gets bigger and bigger.
I've had really good experiences with Amazon, but I try to buy elsewhere if I can. If a product is the same price in two places, then I think it's a good idea to spend your money in the place where an individual is more likely to benefit from your money, or employs locally, or is less likely to create a monopoly. You likely won't change the world, but you might keep someone fed or employed by taking a moment.