We were there a few months back as a family of 4. I'd say our most expensive meal, and the only one we had planned before we landed, cost about $250 USD (a theme restaurant we thought the kids would like). Our cheapest may have been a noodle place in Shibuya Station, which was about $20 USD for all four of us. We often ate at conveyor belt sushi places for around $40-$45 USD. We found it a lot more affordable than we were expecting.