DirecTV defines their "free standard installation" as mounting the satellite dish on the roof. The installer will want to charge extra to mount the satellite dish on a pole in the ground. Some people have stated that they've negotiated the price of the pole-mount install down, sometimes even down to $0. Ultimately, it's between you and the installer - DirecTV would not quote me a price up front for what the pole-mount install would cost.
So check with your installer up front to work through how much their installation will really run.
Bill