You'll just be 'swapping' the 2 batteries you get with the kit back and forth off the charger, no need to buy a spare..but, DO buy some spare atomizers!! If they crap out on you, no vaping. AND, get some liquid, the pre-filled carts only last 15-20 mins before they start to dry out.
Or, if you CAN swing it, order the EGo.
Good luck and we're here if you need us! (Expect for the good Col., we're going into the closet together for a little while..

)