Best Buy via eBay offers the Logitech TK820 Wireless All-In-One Keyboard in Black, model no. 920-005108, for $69.99 with free shipping. That's the lowest total price we could find by $10. It features a built-in touchpad.
Note: In order to redeem the rebate, you'll need to activate the Total Defense software, which involves providing your credit card information. However, you can cancel the service at any time within the first year without any additional charges.