Best Buy via eBay offers the Logitech M720 Triathalon Multi-Device Wireless Mouse in Black, model no. 910-004790, for $29.99. (Amazon has it for the same with free shipping for Prime members.) Opt for in-store pickup to avoid the $5.49 shipping charge. That's the lowest price we could find by $10. It features 1,000dpi max sensitivity and USB and Bluetooth connectivity.

Update: Specs corrected.