I don't think you'll be satisfied with house paint.

Your airless rig will give a better job than you might think! Depends on your skill level. <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" /> And, I think Imron and Awlgrip can be sprayed with an airless system.

Are you sure you want "shiny"? If you just wet sand any of the these materials with ultra fine sand paper, you get a very smooth, flat finish which hides any number of flaws. Also, it is easier on the eye in bright sun.