But this is just a map of the lower-priced items, which are available everywhere. You can find a cheap sandwich, bowl of soup, slice of pizza, or taco virtually anywhere. There is no corresponding standard point of comparison (no "gallon").
The unit should be a Meal. Not just an appetizer, a full meal. (Does it include drink? In US, many places give free tap water, but not others. Is it okay if it’s only lunch, or should it be available for dinner too? What about tipping?)
It's a little different, instead of maximizing gas/price they're maximizing community rating subject to 10$ limit. I have often wanted to query google reviews in this way. I think yelp might have let you do this back in the day. If this data is already being scraped continuously what I'd really like is a query interface.
GasBuddy has a standard: price per gallon
But this is just a map of the lower-priced items, which are available everywhere. You can find a cheap sandwich, bowl of soup, slice of pizza, or taco virtually anywhere. There is no corresponding standard point of comparison (no "gallon").