Surprisingly, what appears to be good quality flex is available on Amazon:
1.5" White PVC Flex
1.5" Black PVC Flex

2" White PVC Flex
2" Black PVC Flex
You glue PVC flex just like PVC hard pipe using standard PVC fittings, with one VERY IMPORTANT difference: the pipe tends to slip out of the fitting, so you must hold it in place for 60 - 90 seconds. Otherwise, you'll end up with a bad joint.

Connecting it to your existing gear is something you'll have to work out.