Natsu

decent, cheap, a classic. perhaps not the supersuperbest makis i ever ate, but you can't go wrong at these prices. oh, and you always get a shot of sake while u wait.

best halfprice sushi in vienna, nicer interior than natsu gumpenfdorferstrasse and about 50cent cheaper than soya in mariahilfer strasse. i recommend the chirashi sushi (which is sashimi on a bed of rice with sesame.
big sushi set is ~6 euro.

Very, very low prices.

Concerning the dangers of sushi: I have a very delicate tolerance threshold regarding fish and sea food, so I sent back the surimi (fake crab meat) sushi.

The rest was fine, we had tons of sake-sushi that tasted neither frozen nor off.

Edit: I just noticed that there are two Natsu restaurants, Gumpendorfer Straße 45 is the one where I ate. they share menus and advertising, so I presume they are very similar.