Here's an idea for one seeking free materials:
Go to a local establishment, this includes a nearby library, hospital, senior citizens' center, etc. (any public venue basically) and find a nice rail, bonus points for finding a kink rail. Take a hacksaw to the base of the supports and then just strap that baby to the roof of your car. Remember to hang a red flag from the rail while transporting it or else a cop will pull you over (you need that red flag, it's the law).
Easy, and free.
Haha, that's hilarious, so you better not forget the red flag to not get pulled over for transport, but stealing a handrail is ok
Not knocking you, I just think thats funnier than shit.
Oh yeah, and fuck the hacksaw, get a cordless sawzall to fly through it. You could probably get a handrail removed in less than 10 minutes with one. On a side note I wouldn't reccomend using pvc because it will more than likely crumble under the weight of a human being, especially with the force you on a snowboard could throw at it.
I'd use wood if you don't know how to weld but if you came to me (I'm a welder) I could probably whip something up for you out of square metal tubing for around $100 and it would maybe take me all of 1 hour or so. Then you just need to skin it with whatever they put on those boxes to make them slick.
Check local welding shops and give them a rough drawing, you'd be suprised how quickly and inexpensively something like that could be built.