Here a nice fellow named owen is working on a year and a half long project to build a CNC sheet metal cutting system. It uses a 100 watt CO2 laser. there are some videos of the laser on his site, a blog chronicling its construction. the cost of the project ran about $12,000. The laser was $6500 from Ebay optics $3500, cnc table was $500, and I there were many ancillary costs.
plasma cutting is a large scale procedure, thing not great for fine detail, it also has its limits on thickness, but the advantages are the surface finish is exceptionally smooth and the cut is very high quality. Most cnc laser cutters trace a very fine path which is almost comparable to wire EDM. Compared to laser or wire EDM the plasma cutter is a much rougher cut.