Collage Video (collagevideo.com, 800-819-7111) sells several at prices ranging between $10 and $25, as does the Arthritis Foundation Store at afstore.org or 800-283-7800.Also see go4life.niapublications.org, a resource created by the National Institute on Aging that offers a free exercise DVD and book that provides illustrated examples of exercises you can do to improve your condition.