Hi.
Finding deployment kit parts for a ERMA is like looking for a needle in a haystack.
As for you're search try contacting the producer of the iron sights.
There is one guy here i've seen owns one of these.
But these rifles are extremely rare. Steyr bought and later closed ERMA, could try contacting them but don't expect much of a proper answer.
Your best shot at locating anything for these would be in Germany where at least 90% were sold.
I am not sure what happened to the majority of these rifles as they we bought by the KSK and GSG mainly, I suspect some are on the civilian market today.
Sorry can't be more helpful then this.
