Comment by ElevenLathe

I once had the idea to do something like this, though the intention was to pitch it to gas station operators as a way to keep their prices competitive (i.e. alert them when the station down the street drops their prices so that they can too and not lose business to casual price shoppers or, alternatively, when the station down the street raises their prices, so that you can too and not lose revenue needlessly) and learned that there are a couple entities, at least in the US, that have national data here. I couldn't even figure out how to contact one, and when I called the other I was essentially laughed off the phone by someone with a VERY New York accent -- it seems from context that their data is VERY expensive and used by Wall St. types, so the idea of some nobody from flyover country essentially reselling it to mom & pop gas station operators was funny, and out of the question.