"Con area" can have a much different meaning depending on what the OP is thinking of. Are you looking for something within walking distance to the hotel where the convention is? Or something in the general Portland area (since your location does say you're from Alaska)?
If the con area you mean is walking distance to the hotel, there isn't any sushi available except if you want to walk across the I-5 bridge to Vancouver, which is a couple miles to walk. If you mean the Portland area there are like 40 restaurants various people can recommend.
Sushi Land aka Marinepolis is my favorite, and they have another location about a block from Lloyd Center too.
The cheapest sushi I can recall finding is Umenoki in the Mall 205 area, which is right off of I-205 at Stark St, on the east side of the freeway, in the strip mall that faces the freeway.