Pay what you wish.

Sonic67

Annalakshmi - Wikipedia

Annalakshmi is an international chain of vegetarian restaurants operating on the uncommon principle of trust in humanity, as it encourages patrons to pay what they believe is fair.

Sonic67

Something similar in London.

This pay-what-you-like vegan restaurant is apparently London's best restaurant

IronGiant

While it's an interesting way of judging in a TV show, I'm not sure it an economically viable business model.  It would be nice if it were though...