I go to used to go to Ko 2 to 3 times a month for the dollar sushi nights (Sunday AND Monday). Dollar sushi nights used to feature around 10 rolls at discounted prices, each week a few of the rolls on the dollar menu would differ from the ones offered the week before. The service was HORRIBLE, but the sushi made up for it and at $1 a piece you are paying around 70% of normal price (and since they are so overpriced at Ko to begin with this meant you were paying what you would pay anywhere else).
Lately I've stopped going to Ko for several reasons. The dollar sushi menu no longer changes. It is nearly CONSTANT from week to week. Sure it's a super discount so you can't complain too much. However, sometimes some of the sushi you order comes to the table reeking of fish. The pieces are $1 because clearly the fish is old. And finally the service is utterly horrible on Sunday/Monday nights. Sure they are busy, but the wait staff simply suck.
To sum it up you can get sushi that is just as good and just as cheap at several other places in Champaign/Urbana. Branch out a bit, trendy neon lights that change color don't mean the food is good.