Find a Tennis Racket either new or used, a can of balls for around $2. and go to a free public court. Enjoy an hour of exercise outdoors and when you're done, the racket and balls will fit snugly in the trunk of your car or in the hall closet for the next use. Sorry, they're not good for hanging clothes on them like the $800 metal contraptions that are sold on TV.
Spend the $800 on lessons or a tennis camp down south this winter and you will have a sport to enjoy for the rest of your life.