I've often wondered about this, as the ingredient, labor, and capital costs are all pretty low. Sushi grade fish is on the order of $15-25 per pound retail, perhaps $10-18 wholesale. That's the good stuff like ahi, salmon, hirame. Rice is nearly free and you get 25-30 pieces out of a pound of fish, so the ingredient cost on two salmon pieces you sell for $4 or $6 is about $1. Things like octopus, squid, eggs, aren't expensive at all.