Nikon Japan announced a new DF-GR1 grip for Nikon Df camera. Shipping will start on February 5th, 2015 and the price will be ¥16,200 (around $130). There is no indications if the DF-GR1 will be available for sale outside Japan (still not listed at Nikon USA), but you can already buy one from eBay.
Third party manufacturers are already selling battery grips for Nikon Df cameras (now available also on Amazon).
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