Thank you for your answer!
Yes, as I researched myself, I found some (very old) listings with an amount of up to $400. But I think, today and in NOS condition, the price of these original parts are higher... I don't know how hight exactly. I was asking because someone is very interested for my RPM and I don't want to give away this gem under its price. It's an original Buick RPM.
Thank you also for the link, I will follow. π