Matuba all you eat sushi lunch buffet is a good deal. It's about $14 w/o drink and tip. They only have it on Tuesdays-Fridays at their rotary bar. They have some nigirizushi, rolls, temakisuhi, salad, dumplings, chicken teriyaki, and other small dishes. It's not a big selection but it's very tasty. There's also a dinner buffet there but I've never been.
Their regular lunch menu is also a pretty good deal.