Buy fitness gear from discount sites or on sale: If you shop around you can get a full outfit for under $50! I included some of my favorites from all over (most have free shipping) and all items are under $10 each.
Athleta under $10
Boohoo under $10
Forever 21 under $10
Zappos under $10
Old Navy under $10
Bed Bath and Beyond
Ask for discounts: insurance companies and employers if they give reimbursments or discounted membership rates.
Compare gym options and negotiate
Buy classes in bulk:
Use a home gym: buy workout equipment and use at home videos
These pieces are also under $10!