'The popcorn will come at a cost', 'The popcorn is just not free', 'The popcorn Price $10', 'You need to pay for the popcorn' or, simply, 'The popcorn is not free'. The statement, 'You normally takes your little one around the flight free of charge' would be in opposition to 'You will need to spend to choose your little one over a airplane' or 'It