how bad is the tear, and where at on the seat? is it repairable?
reason being, I used to laugh at the vinyl/leather repair kits ads I saw on TV, until I had occasion to actually use one to repair a missing chunk of vinyl on a 2007 tahoe seat. it came out incrediblely well, was pretty easy, and took a few minutes to do (and about 2-3 hours for the base adhesive to dry)
just a thought, and I'd bet the results would likely be even better on a used seat!