I have training guns. I would say the majority of users here have training guns. Malfunctions are not world ending. Shit can the offending magazine and drive on. If the problem persists amongst the entire cadre of mags its more than likely the mags if you're running a quality gun.
ETS is also really good about replacing magazines that don't work. I had one issue with an earlier generation 17 round magazine that was replaced no questions asked. The replacement works great and has thousands of rounds through it at this point.
Fifty dollars is 350 rounds for me. Id rather have the 350 rounds.
I will agree with you that if the magazines don't work then obviously it's a total waste of money. If they work then what is the issue with saving money in a non critical area?
I can appreciate that HK makes a really good magazine but once again, they're not affordable comparatively speaking. They also wear out a hell of a lot faster than a gun. A magazine is consumable. In that vein, if im spending less money to get the same result, im going to spend less money.