I came across this (older) thread and glad I did. Was planning to purchase one and have been looking at eBay as an alternative and had found these guys:
Nissan 370Z No Convertible Painted Factory Style Spoiler Wing Trim 2009 2014 | eBay with a price of $220...
Now seeing this supplier ( WingTech) and reading through the thread they appear to provide a quality product.
They don't show the pricing any longer so I sent off for a price quote and will follow up to anyone interested in this thread in case pricing has changed.
Still curious if anyone has (or is) planning on the duckbill (carbon signal CS Z34 Type - N) option. Love to know anyone with experience on it. Pictures preferred.