The pricing for Izumi annoys me a bit. First they charge $5 per person for dinner just to get inside, and then the menu is ala carte pricing. The price of dinner depends on what you order from the fairly extensive menu. Individual items are not expensive - I think the highest price item is around $6 or $7 - but you will order more than one thing.
Also - booking Izumi online does have the $10 per person fee unlike the $5 per person fee if you booked on the ship or just showed up for a seat. But if you booked online the $10 you paid essentially covers $5 worth of food.