Yeah, schedule 80 stuff is pricey. But the grey electical sch 40 pvc is half the price of white pvc sch 40 which is about 3/4 of the price of cpvc. I dont know how long cpvc will last outdoors, but probably longer than plain white pvc.
Thats the situation on the pipes.
For the fittings, common tees and small elbows for grey electrical sch 40 arent carried locally (couplings are though) and have to be special ordered at a higher price. Sch 80 are also expensive. White sch 40 fittings are the cheapest and because they are thicker than the white sch 40 pipe, they will naturally last longer outdoors than the white pipe.
Some latex paint sticks very well to pvc, while other latex paint will peel from pvc fairly quickly, Ive observed. There is Vinyl Color spray paint sold at auto stores which is really a dye instead of a paint and sticks to pvc very well. The ordinary cheapest spray paint will also stick well if used in thin coats, as evidenced by graffiti everywhere heh. Thin coats of any paint will last longer than thick coats, as thick coats have a tendency to peal. Pretty much any paint is better than none for long term protection.
Yeah, Ive read the light color vs dark color debate on various paint websites. For most people, theyll want to use a color to make the antenna inconspicuous to the eye. Flat colors will do that best.