Not sure how big the demand is for a replacement / replica brace. We sold over 100 x OEM W braces this year alone, 40 more pcs arriving tomorrow. The other traders are also selling lots of Nissan OEM braces, too. Nissan dealers also sell these directly, although a bit more expensive.
Probably it doesn't matter too much for a normal car, but to me the airflow appears to be better on the OEM brace?
Also, if it lasted 12-15 years on your car, surely that's long enough considering the salt on the roads and the humidity here. Put some protection on it when you fit it and you should be fine for many, many more years.