Your local high-school might have a gym...

My kids' high-school has a gym that is equipped with a lot of newer exercise equipment that they allow the parents/families of students to use for a very cheap fee. We pay ten bucks a month to use it as much as we like.

The only issue is, you can obviously only use it before and after regular school hours. In the summer time it's open pretty much all day long, 6 days a week though.