I may be biased, but I think it is fair to say that the laser guide star is one of the biggest advances in ground based astronomy since the technique of adaptive optics. Current LGS laser systems still cost millions of dollars, but I expect that cost to drop considerably in the next few years.

The Keck II laser was the first laser guide star system on a large scope, and the results have been phenomenal. Gemini North now has a laser, and in 2007 Gemini South and Keck I will get lasers (My next big project). Subaru is also getting a laser. by the end of 2007 I expect there will be 4 lasers on Mauna Kea. Other smaller scopes are also getting laser systems.

Currently, there is no established vendor of such laser systems, but that is changing. Every system that exists is unique. The Keck II laser is a dye laser- it is large and complex, essentially 9 laser subsystems that have to work together. It cost ~6 million dollars. The laser at VLT is also a dye laser, I think it is safe to say that future systems will not be dye lasers. They are messy and inefficient.

The Gemini North system is a solid state laser- it mixes 1064 nm and 1319 nm light from 2 Nd:Yag lasers in a nonlinear crystal to get 589 nm. The Gemini south and Keck I lasers will also use this process, but using different technologies.

Work is being done to develop a fiber laser system at 589 nm. I feel that a fiber laser is ultimately the way to go, but the technology isn't quite there yet.