For the front lip spoiler thingamajigger, I got some black PVC conveyor belting from McMaster-Carr.
www.mcmaster.com
And type in the number 6001K808 in the find/search field.
Then click on Catalog page.
I initially bought the Black PVC 4" wide, 0.17" thick belt. It seems slightly thinner than i'd like. I think i'm going to get another length of the 0.21" belting, which is closer the the thickness of my existing OEM Porsche rubber front spoiler.
I'll post a picture of the how the belting looks when I get home. The outer surface is kinda shiny, but looks okay. Price is not bad at all. $1.27/ft.