Exactly what it says on the tin (or copper, depending on what ore your world generated with). The requirements for this happening is the Mechanic being present and the Golem being defeated.
~~Prices~~
All of the traps' prices will be 5 silver coins, except for the Flame Trap, which will be 10 silver.
~~Prices~~
All of the traps' prices will be 5 silver coins, except for the Flame Trap, which will be 10 silver.