If you would like a private cabin (for two people), one way trips start at about $6,000 for a couple, and the nicer cabins are $20,000.
If you want to just have a chair for 4 days (you don't want this), then it's about $1,200 for a couple.
If you use an airline like Lynx, you can find some deals for less than $150 for a couple, after all the charges, and it only takes 5 hours.
Trains are basically not usable for distance travel in Canada in their current state. I wish they were, but they're not.