Logitech has the Logitech M310 Wireless Mouse (Dark Aces) for $15. Add two to cart to reach $30 - $8 off with coupon code logi_m310_71312
[Exp 7/16] = $22
with free shipping. Features nano USB receiver, contoured shape with soft rubber grips, 2.4 GHz wireless connection, and about a year of battery life.