I have always enjoyed Kofusion. I wouldn't say it's the best sushi in Champaign/Urbana, but they do have some fun and interesting rolls to try. To date, they are still the only place locally I have found that has a roll with raw jalapeno, one of my favorites in sushi. Honestly, they'd probably get knocked down a star if it weren't for that one delightfully spicy roll.
I've not been for dollar sushi days on Monday, but it sounds like a great way to try new rolls.
Their lunch buffet is pretty good. They have a limited amount of sushi and what they do have is pretty safe: california rolls/fried rolls. They also have curry and salad on the buffet. It's a little pricier at over $10/person, but the food is good. Definitely worth a shot if you're interested in checking out some safer food options. For me, I want all things spicy! And they only really have wasabi for that.