Gaiam Balance Ball Chairs are available for just $54.98 today (30% off).  Remember prices may change, and this price will not be valid after 1/3/18. You can also find a variety of seat covers for the chairs.

• Created by leading health and fitness experts to improve your back health
• Employs the same balance ball used in your workout routine. Helps build a healthier back, align the spine, relieve pain, and improve your overall well-being
• Includes removable 52-centimeter Balance Ball, an adjustable support bar, easy-glide casters, air pump
• Designed for users 5-feet to 5-feet, 11-inches tall; 300-pound weight capacity.
• Note: for optimal performance, it may be necessary to re-inflate your new Balance Ball once or twice after the initial inflation