The smaller the band, the less the cost. And, if your not that huge, say your playing 1K clubs or less, you can get buy on rented equipment and little to no crew, so you only have to bring your instruments, which really lowers the cost. If you're doing a stadium show, all that staging has to be either dragged or built there - either way, its a huge expense. And you need people, people who don't come cheap (at all, bargain basement roadies is going to make $1,500 a week, plus per diem, plus hotels, buses, and airfare - the big techs are going to be making $700 a day, plus all the rest, one tech per instrument - that runs up a huge bill very fast.)