I've had the $25 model, and now have a rebounder that lists for about $300. For explosive jumping,(feet leaving the mat), the better unit gives me a much more stable, secure feeling, but for the gentle movement, which is all that is required for lymph, I don't feel enough force is generated to hurt the joints. My 84 year old mom uses the cheaper one now, from a seated position, lightly gripping the edge with both hands, legs extended and feet resting on the floor. She has had great results and no complaints. When caught without your rebounder, you can 'pretend to jump' repeatedly on any surface to approximate the movement and the benefits. Make sure to keep the movement very gentle.