You buy tickets that are $6.00 each per person for one round trip at the check in desk at the resort. If you have 3 or more folks in your group it is cheaper to drive your car and pay the $15.00 disney parking fee. The Disney fee is good all day long at any park. The bus ticket is good for only one round trip so if you want to come back to the resort for a rest in the afternoon you would need more tickets to return to the park that evening.