The only flexible downspout extensions that are available
in the local supply stores are made from vinyl.

The problem with vinyl extensions, in my experience, is
that they only last a few months before they are cracked
and fractured in multiple places. I don't know if its
exposure to the sun, cold, or what but they crack and
need to be replaced very often.

Is there a durable alternative or is vinyl the only material
available for flexible downspout extensions?

I can't cobble together several rigid aluminum extensions because
I need to swing the whole unit around to move cars, trim
grass, etc.