I would reccomend Krylon Fusion. its a plastic bonding paint. This is comming from a nawb so dont take it too serously, i am a graff artist so i do love spray paint though. I would rough the PVC up with sand paper, hit it with some Krylon and then depending on what you use maybe some clearcoat. Fusion useally has a fair amount of clear coat in it. If you want to get really good paint and its available to you check out Montanna Paint. Its ten bucks a can but boy is it worth it!!! IMO that is...lol