I know it's not quite downtown but Memories of Japan - 900 Don Mills Road (Just past Eglinton). For 14.95 - 16.95 (depending on what you order) you get a multi-course meal consisting of salad, sushi, noodles, main course and green tea ice cream. You can choose teppanyaki style seating or just regular dining room.
I too have been to Yamato, in Yorkville. It is not cheap, but it is good. I recommend the steak teppanyaki (they chop it up into cubes and it is really good). The others are ok, more ordinary. The sushi there is a bit more pricy than other places, but extremely authentic to Japanese cuisine. I don't think Toronto gives their sushi enough credit... it is very rare to find good authentic sushi in this town (and when it does exist, they get overlooked a lot because of price point issues). Their California rolls rock and so do their Assorted Sushi combo (for $12.50, i think?), and so do the Futomaki rolls, and the tempura too... everything!
Frances in Toronto