You're basically asking to take on the role of concert promoter. That's basically how bands end up playing in certain cities. The promoter goes to the band and says, "I'll pay you this much money to come play at X city at Y venue," and then books the band. On the other end, the promoter calculates how many tickets he can sell and at what cost, books and pays for the venue, pays the band and other costs (like ticketing, insurance, press and promotion, transportation, hotel, security, etc.), and what's left is the promoter's profit.
Here's an overview of what a concert promoter has to do, to give you an idea of what's involved.
http://www.concert-promotions.com/concertexcerpts.html