As described, that's just way too complicated. It also fails completely as advertising since the people have to start out wanting to eat or shop at the place.
You are missing the point: if it helps you fill tables with customers, it is good advertising regardless of the customers being new or not. Also, how is an offer based on what you know people want worse than one published to the general public in, say, a newspaper ad?
Customers proposing that a store they know about and already wish to shop at lower their prices is not the same thing as "advertising". To call this advertising as you just did is a misnomer.
