I am not so sure it would cost that much more--PVC pipe is cheap--the sheet
metal work would be in expensive--I have used galvanized sheeting to make
"squirel guards"--cutting with normal tin snips and pop rivets to close the
cone.  My guess is that it would cost no more than wooden pilings--and would
be much easier to put the pilings in.  The 30 foot wooden pilings are very
heavy and difficult to balance on most small pier barges with A frames.  There
are several articles that suggests that the Navy has concluded that plastic
pilings are less costly than wooden pilings.  The Corp of engineers estimates
the cost of wooden pilings at $ 10 a foot--or $300 a 30 footer.  That is a bit
high for residential pilings--but I can check with the local supplier. ( our
group on Bayou Chico has a barge with frame and several pumps, so we set our
own pilings---when I moved I had to hire a piling setter--and it was $$$.

Bob Austin

I used to pay $100 for the piling and $100 to drive it in, but that was 5
years ago in RI. I tried sheathing them in PVC after they were in to prevent
the ice from lifting them, but it was only marginally successful.  I found
the best tactic was ice-eaters rotated as needed during Janu8ary and
February.

                                      Regards....

Phil Rosch
Old Harbor Consulting
M/V Curmudgeon MT-44TC
Currently moored in Oak Bluffs Harbor, MA