An auto place called Princess Auto, known by most Canadians, has a lawn tractor battery on sale for $55.

https://www.princessauto.com/en/gcu1...t/PA0008680548

A few people are not happy with them but Princess has a really good return policy, and the battery has a no questions asked 6 month replacement. I figure it's good enough to start my 14 Mirage for a couple of years.