There are sliding scales of sushi in Vancouver.
Most places sell sushi a-la-cart, and it's relatively inexpensive. $4-6 for a single roll cut into 4 pieces. $12-15 for a combo plate with several varieties. It's hard to walk a block in downton Vancouver and not come across two or three of these restaurants.
All-you-can-eat sushi restaurants are a little harder to find. I've eaten at Tanpopo (good) and Richmond Sushi (very good). The food quality isn't much better than the a-la-cart restaurants, but all-you-can-eat restaurants usually have better seating and drink options. Expect to pay $13-16 per person, plus drinks and gratuity.
The top notch sushi is prepared and sold in many fancy and expensive restaurants. If you want real 'Japanese' sushi, with a Japanese trained sushi-chef, you have to look at one of these places. I was about to recommend Yoshi Japanese Restaurant on Denman, but it appears that it has closed. Vancouver.com has a top-five sushi restaurants list
here.