I wanted a quick paint job too, so I bought some matte camo-like colors (Oregano, Honey, Fossil) from the local hardware store (Lowes). I chose to take the tank completely apart, and remove the detail items, but that's not totally needed. Some random holes cut in cardboard sheets served as the masking. I played with different elevations to get just the right misting effect. Oh yeah, I hit it with primer first, and also made sure all the flashing was cut off. Not bad for a cheap paint job.

Here are the results: