Urethane or fiberglass, I don't care. I will make offer if someone has one!

They're not very expensive; you may wish to just buy one new:

http://www.zcarparts.com/store/merchant.mvc?Screen=CTGY&Category_Code=7AD1

I have of course already tried to get one from MSA and all other possbile vendors...NO ONE has any in stock...back ordered till the end of the month...I am moving out of state the end of this month and wanted to get the air dam installed by the shop that knows my car and has done all my previous work.

Is a stock valance ok? Les at classicdatsun.com might be able to outfit you with one of those and a BRE front spoiler. Not sure how much that kind of thing will cost, but, it might be worth it.