You are simply not going to find rare and cheap in the same meal. The best you are going to do is remind people of food that they haven’t had in a while.
Or you can define uncommon as food that people generally don’t eat. Insects, for instance. While bugs are incredibly common, most people do not consume them in great numbers.
Happy now? Sit down and eat your potatoes.
I thought Monty Python was the snake from Harry Potter.