i've got one of the generic "Red and Black" lasers off ebay. Its a 36x55 cutting area and 130watts rated tube. For the $$$$, its been an amazing investment as it saves a TON of time in more ways than just cutting wood.

Like Paul said, i mainly use it for "organics" and some other things ( such as etching coated metals, tiles, glass, etc). For hobby stuff, i use it mainly for cutting balsa, ply, Thin G10 (anything under 1/32"), raw fiberglass cloth, kevlar, plastics and papers.

I have cut Carbon with it, but its a very bad cut and if that is what your looking at it for, you really need a Cnc router ( I have one of these as well and it gets all of my CF/G10 and composite sandwich cutting tasks).