This. My old band did a european support tour for another more well known band a few years ago, 2 of the arena shows in Germany and Italy took 20% from all merch sales, we either had to accept using their vendor or not sell any merch at all. In reality we had to increase the price of our T-shirts and records or face making a huge loss from the run of shows. I guess for headline bands using their own selling methods at gigs its different, I probably wouldn’t increase the price at all.