The laser module, the scanhead that moves the laser beam through the lens, the f theta lens and the control electronics and software make up much of the cost of a laser marking system. Workstations, enclosures and motion systems (X,Y and/or Z) add further costs to the system.
It is impossible to know the cost of a system without knowing what it consists of. Setting aside motion systems and automation, a laser marker mounted on a versatile Z axis workstation with a 20 watt fiber laser should have a price in the $45K range. This assumes that quality components are used throughout.