You may have to look for sources of 3D-printed figures, like Shapeways, or vendors who offer figures in scales of your choice. 1/18 isn't too common among commerically-produced figures.
If you're not averse to converting figures, the second generation GI Joe figures from the 80s are in 1/18 scale. Also, the large aircraft models that 21st Century Toys sold back in the 90s and after were in 1/18 scale, and they included pilot and gunner figures. They are toy-like, too, and articulated, but they could be kit-bashed or super-detailed to more of a scale model quality.