sentences:  Elon Musk said the service would be offered for the price of about of gasoline at the current local rate, around to at June 2013 prices.Owners could pick up their battery pack fully charged on the return trip, which was included in the swap fee.Tesla would also offer the option to keep the pack received on the swap and pay the price difference if the battery received was newer, or to receive the original pack back from Tesla for a transport fee.