A 5W single frequency CW green solid state laser (532 nm) from Coherent. Note the small size.

Additional information regarding these lasers and why they are useful for making holograms is included in HMP 6 Chapter 4 - Lasers: Current Trends.

Total cost for HMP6 Delivered airmail to your door:
$30 (USA) (UPS ground)
$35 (Alaska, Hawaii, Canada, Mexico)
$45 (all other countries).