Green one...
My son just came home from a week with his mother in Thailand. In his luggage is a green laser, purchased in Pataya (or whatever the place is called) labelled "30mW, 532nm". It is powered by two AAA size batteries, and let me tell you, the thing shines!
We pointed it at our church across the bay, a distance of slightly less than a kilometer, and see a spot no more than an inch or two in diameter! How's that for collimation and coherence? I have never seen a LED-based laser with such properties.
So, rest assured. You can get these thingies with really high power really cheap - he paid £22 for it!
Needless to say, he has been given a lecture about where to point it and where to not point it...
/perf