Dulux do upvc paint. No need for ''specialist'' paint or spray equipment. They only do it in white (at least last time I asked them) but I see no reason why you can't get it tinted by your trade supplier to whatever colour you want. Just remember - don't sand it down
Dont paint uPVC. For the best results, if it needs painting, replace it. IWS: Information With a Smile
You do not need UPVC in mahogany. You need to use Zinsser Bulls Eye 1-2-3 Primer then you can use any topcoat over it
It seems there is a lot of confusion regarding painting PVC. I found an excellent resourse on painting plastic from Thai Plastic wood after a friend of mine made an excellent job of painting a garden office that was clad in PVC. Check out; http://www.thai-plastic-wood.com/painting-plastic.html I hope this helps to clarify your options.
Not sure if it's the same stuff but in 1994 I painted my plastic guttering and downpipes with Black Gloss Dulux Weathershield. Dulux advised me to rub down the surface using fine wet and dry first, used wet, to provide a key. I recoated it for the first time a week ago, after rubbing down again etc. There was no sign of peeling after 17 years so it seems to work. HTH Brian