Manti, some stock brokers will give commission-free trades to their clients from time to time. You just have to know how to 'front' for yourself and have a more flexible thinking broker.
Yes, I have been successful in getting free trades from my broker. But I don't beat it to death. I pick my spots carefully say maybe once a year.
It helps if you have a good plausible-sounding lead in (segui) to your request.
So, from my personal experience, it is possible that Jagman (or others) could trade occasionally commission-free. Because I do.