It isn't so much dollar inflation as much as it is constrained supply. While this may be part of it, other guns haven't gone up by 200% in the same time.
Those $99 Norincos haven't been allowed to be imported for two decades. The $150 like new Yugos have all been imported- there aren't any more of those either. The Russians and Albanians were never brought in in huge numbers.
When plentiful supply dries up, prices climb. Especially when people are into semiauto intermediate caliber rifles in increasing numbers.