The yellow jersey was a limited run. We're not one of the big markets, so Adidas gave RSL a limited supply of the jerseys to sell. IIRC, it was somewhere between 100-150 jerseys, and they were gone before the game started on the day they were made available. They were authentic jerseys, so they were sold around $75 each, so they had to have made some money on them. Trey Fitzgerald talked about this at the beginning of the season. He said that Adidas only gives them a certain number of kits each year, and if they need extras they pay for them. Basically, he said they have to make each kit last two games. I wonder if that's different for other teams in MLS.
It's all about whatever type of return they might expect as to whether or not they'll keep it around $75 is a good price for authentic jerseys. I imagine that, in Rio Tinto, they could have sold more than 100 jerseys, but Adidas has their business model. If they wanted to sell more, RSL likely would have had to order them on their own dime and risked taking a loss. They probably could have sold a couple thousand if they wanted to. I wouldn't be surprised if the circumstances might be different for a team like LA, but since kit providers are contracted league-wide, I doubt it. Big clubs like Chelsea probably never see them again after one game.
