Today only, Meritline offers the Logitech M570 Wireless Trackball, model no. 910-001799, for $28.99. Coupon code "MLCV27WN" cuts it to $24.99. With free shipping, that's $2 under last week's mention and the lowest total price we've seen for a new unit. (It's also a current low by $5.) Features include programmable buttons, 2.4GHz wireless, and up to 18 months of battery life.