^ sums a lot up
If you're looking for something bright: green is the way to go. 200mW of green should be as bright as many of the 445nm (dark blue/royal blue) lasers (200mW green = 1500mW royal blue for beam? I think?). If I were looking for a green now, I'd buy from the jetlasers group buy. One of their 600mW units peaked 1204mW (or something) for another member, get 'em while they're quality.
However, I'll add: There's a few "main" types of blues, I assume you're looking for a handheld. Most common now are the 445's... they're everywhere. beam's pretty bright, my friend managed to see it from his house about 500 meters away. But, if you want something more exotic, try looking for
Lasever.com, the owner, David, sells some nice "light blue" 473nm lasers "cheap" (cheap compared to other stores, i got 100+mW of light blue for $390
) I have a personal preference for lighter shades of blue, just more "easy on the eyes". Beam's pretty visible at night, not as well as 445nm, but that's due to the lower power.
Yellow: if you're looking for a unique color that rarely anybody has ever seen, this is the most accessable out of the bunch. Not too bright in "readily available" powers, but worth it IMO. I need one soon... Try looking at laserglow's 593.5nm
Rigel 6, best buy currently out there. However, I prefer the slightly more yellow side of things so I plan on buying the rigel HV or the HV pro. (589nm)
Go with whatever sounds best to you at this point, let nobody fully choose your own decisions
Hope this helped,
-Zach