Amazon has theLogitech M570 Wireless Trackball Mouseon sale for$ 20.25withfree shipping.

• Sculpted trackball shape supports your hand and stays in one place
• Connect up to 6 compatible wireless devices with a tiny receiver that stays in your laptop
• The laser trackball offers smooth cursor control anywhere with precision laser tracking on almost any surface
• Control your laptop, desktop computer or home theater PC wirelessly from up to 30′ away on Windows or Mac OS
• Long battery life can last up to 18 months

Highly rated with 4.5 out of 5 stars from 9,462 customer reviews. Also, rated Amazon’s#1 Best Seller in Computer Trackballs.

Most merchants have this model priced at$ 27.99 or more according toGoogle Shopping.