Sandy,
The lady and I will be building curtains into our JK for the sake of a camp shower (Well, more for the sake of people not being able to see us while we use said shower, but you know what I mean!)
Fabricland here in Canada -- and any large fabric store -- should sell various screen stuff by the metre (or foot). Couple that with some stick on Velcro, and you can make your own fairly cheaply.
This assumes you don't mind having some adhesive velcro strips on your hard top.
If you have a soft top it may be a bit more difficult but still, the homemade route is always an option.
Regards
Craig