Glock did crazy deals early on, letting US police departments trade-in their existing used guns from other makers for new Glocks at minimal or no cost.

Glock could afford to do it because Glocks are cheap to make due to the brilliantly simple design, with a manufacturing cost lower than the resale value of the used guns they were accepting.

Soon Glock owned the US police market, and that gave them the credibility to win in the US domestic market at full price.