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[Best Buy/Amazon] Xbox One S Controller (2016 Edition w/ Bluetooth) $49.99 ($59.99 – $10)(r/GameDeals)
Also available on Amazon for the same price (well, $49.00)
Edit: Thanks to gtmustang for pointing out that this is at GameStop for the same price, too.
Just a note that these controllers are currently suffering compatibility issues with Windows 10 Anniversary Update that hopefully Microsoft resolves soon.