Amazon offers Prime members the Microsoft Xbox One Wireless Controller with Cable for Windows in Black, model no. 7MN-00001, for $39.99 with free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $8.64. Newegg charges the same price.) That's $2 under last week's mention and the lowest total price we could find now by $6, outside of the mention below. While this controller must be used wired with your PC, it can be used wired or wireless with your Xbox One.
A close price: Best Buy via eBay charges $40.99 with free shipping.