It's not too hard to build a sweet rail for 250 - 400 bucks. Thats gotta be cheaper than anything you can buy pre made. This cost about 120 - 150 in 2x4s and we got the quarter inch HDPE for free, but its like... 175 for a 4x8 feet sheet, so thats enough for a few rails.
This thing is a beast, it slides super easy, is wide enough to learn anything on and was almost more fun to build than hit.
Just go for it. For a Handrail PVC will work, but mine cracked pretty fast at 20 below whereas the HDPE has held up for countless hits at -30 F with no issues at all.
Join the build a jib cult.