I've come to think this is actually a large problem. In the subscription model the prices were paid for longer time periods, like yearly, and publishing was fre

I've come to think this is actually a large problem. In the subscription model the prices were paid for longer time periods, like yearly, and publishing was free. The bills went to librarians who managed everything professionally and had a good overview. This showed clearly in the conflict between 'Project DEAL' and Elsevier the last few years, where a bunch of German Universities and Institutes started collective bargaining to get prices down, and even stopped subscribing for a while. Now the bills go to individual researchers who often don't even publish with a specific journal more than once every couple of years. I doubt anyone will keep track how much publishing fees increase. Also it's not really the case that there is much competition, if you can get your paper into a high-ranked journal you don't send it elsewhere to save 500$ or something. Also it used to be that the library subscription budget was clearly defined to the University or institute, now the APCs often come out of one of the many research grants. My bet is that the APCs will increase much faster than the subscription fees did.