Sakura is another of my lunchtime favourites. It's on Liverpool Street, just down from the Commonweath Bank. The sushi is always lovely and fresh, and the sushi man always remembers what I like and restocks it if he's not busy :)
They have the sushi rolls that most places sell, but they also have individual sushi pieces at $5 for 5, $1 for each additional piece. The pic below is what I usually get - 2 tamago (egg), 1 salmon (I prefer tuna but they were out this time), roe, chicken roll and inari. In the bottom-right corner you can see Kewpie mayonnaise, which I am addicted to!
For $6 this is great value.
They've recently started stocking seaweed salad as well, which I adore!