Tyler Tool has the Dewalt 20V Grease Gun Kit (DCGG571M1) on sale for $199.00. That's not a knockout price, but along with the Kit, you receive two free items: a Dewalt 20V Max 3A battery ( Retail $79.99) and a Dewalt 1/4" Impact Driver (List $119.99)
Shipping is free. I have purchased from Tyler Tool many times in the past and have not been disappointed. They are affiliated with, or maybe an alias for, CPO Outlets. Just checked CPO, and they have the same deal.
As far as I can determine, the deal is good thru 6/30/19.