Can any one tell me how the bus tickets work as far as cost. I know you buy them at the tobacco stores but how do you know how much to buy them for. I read that it depends on the time it takes to the destination. Can you buy one ticket that will last a week or do you have to have a ticket for each trip? Also does any one know of the cost of the bus ride from Naples Airport to Positano? Thanks in advance for any bus tips. One more thing, is there enough room on the SITA buses for luggage?