If you're looking for "bang for the buck", only want sushi (and not other Japanese food), and don't mind slightly less variety, Tokyo in Bloomfield should be your first stop.
If you're looking for the best Japanese food in Pittsburgh, Chaya is it. This is the best Japanese restaurant I've had the chance to try. If you like sushi, you should go here and try this.
Even in the new location, there's often a wait, so don't show up starving; that said, the wait is worth it, and the food is awesome. We've yet to find a bad pick on the menu.
5-stars; as good as it gets.