I agree with Kailani and Suntze. But...did you know that Sushi Kaji keeps an outlet within Le Cafe Michi at Pharmacy and Sheppard (strip mall, southwest corner)? Never been to Kaji, but the fish I've had at Michi is the best i've had in Toronto so far, on a par with good shops in Japan. (i lived in Japan for three years so I have a bit of credibility, i hope).
Just go into the back (maybe 9 or 10 seats back there) and order the Sashimi set for 22 or 24$. Comes with quality tea, really good quality japanese rice , miso soup, a nice mesclun salad, and a slice of cake from the front display case. In my opinion the best price/value for sashimi in T.O.
I've also heard good reviews of Sakura Kaiseki on Church, but that's kaiseki food (very fancy), not necessarily sushi or sashimi that I think you're looking for.
I'd also recommend Sakawaya at Jones and Danforth. Koki Oguchi does some good things there, and plays some interesting jazz. Service is so slow as to be glacial, though.
Don't forget Etamae (sp?) just north of Queen st W on Duncan or St Patrick (you can see it from Queen streeet) near Osgoode station. This is real authentic home-cooked food, and sushi was very good, too. Large Japanese clientele. I mean lots, not big people...lol