This is a terrible idea[see edit]. What incentive is there for any store to use this system when they're providing their data in a single easy to query location? Brick and mortar stores have custom because of brand loyalty, a large part of brand loyalty is saying "I shopped around twice and both times x was cheaper, I'll assume x is always cheaper and use them". Now imagine if every time a consumer wanted something t…
Boom, brand loyalty is gone, nobody would go to their "favourite" store any more because there would be no favourites. You are assuming a store like walmart doesn't differentiate itself from other stores by having an easier return policy, or that target doesn't differentiate itself with a nicer store. If you could get 1 store to adopt this system, others may follow since they would be losing out to store 1. Would it…
I'm talking about the "normal" stores, the ones that might have 1 or 2 locations in one city, or have 2 or 3 locations across the country, the stores that rely on brand loyalty and don't compete with their competitors on $0.01 difference.
No small business would ever choose to compete on $0.01 price differences; the idea the OP is proposing would cause exactly this.