It depends on how you do it. Promotions giant Live Nation will do a global buy out for the entire tour so there is more control over the costs. The riskiest part of any act touring is the risk the promoter takes. They will have a guaranteed fee for the act, but then have to ensure they make a profit after that. All it takes is a band member to say something out of line, or for there to be bad weather, to derail a tour. Terrorism is a huge concern at the moment for the live industry. No matter how much you spend on security, one person can still come along with a gun and get in.