... you can search ebay or local surplus-shops for outsourced or damaged laser-systems.
Working NdYAG- or Fiberlaser are good for engraving ... but the pumping diodes out from damaged fiberlasers can be of even better use for SLS or with higer powers (have types with 5, 9, 25, 30 and 200Watts @975nm) can be combined for enough energy to cut trough steel!
Viktor