You can put one of these together really easy these days.
You can also make it pocket portable.
Buy a high powered pen sized diode laser from anywhere that does high powered green diode lasers (Wicked are one, iirc) then buy a small but strong lens to spread the beam out wide. Now add a Fresnel lens to "collimate" the spreading beam. No, it will be far from perfect, but it is flat and light. Now think of a way to position the Fresnel just right, quickly.
If you want better effectiveness, use a cylindrical lens to spread the beam into a bar, rather than a circle, and trim your Fresnel to match, making it smaller. Add a chopper wheel for the flickering effect (don't turn the laser on and off really fast, it won't like it. The doubler chip will get thermally shocked, and it has a long rise and fall time.)
Just be careful what you use it for, and when.
(If you wanted to get really advanced, you could Q switch the output before the first lens to get the pulsing you might want, as well as increasing the efficiency over a beam chopper wheel. The Q switch is a bit like a capacitor for light.)
Edit: Just looked at that site you linked to. That collimator is completely unsuitable for what you want, it puts out a 20mm beam. You'd have to be literally miles away to have a big enough spot to do anything useful. The plain beam would do better at any range you could really see someone at, as it spreads more before reaching your target.