That $50 angle grinder was also a $5-10 chinese one (unless it's from the 60's when stuff was made elsewhere), there was just more middle men and more markup. The internet just placed you 1-2 steps away from the chinese factory, whereas the hardware store in the 90's was maybe 6 steps away from the factory. It's a disappearing problem: soon the used ones will also those $14 angle grinders, so you can get a used one for $4 or a new one for $14.