Try Calgary Seat Cover. They redid my buddy's Nytro seat and it looks great. Lots of selection of vinyl in various colors and grains. They are located on 12 st NE right accross the street from Walt Healy Motor Sports.
If it's for the same vintage of sled in your avatar pic, recreation supply sells pre made ones just replace the old one. The worked pretty good back in the day.
Give Dale a call at Cascade Vans, 403-250-3861, he is located just off McKnight and 12st. Just north of Walt Healy, he does custom anything. Has a really good turn around as well.