Totally agree with you Marcos , most of us know which parts are rare , expensive and NLA , so when these parts come up for sale,( very rarely .. but they do from time to time ) you have to make that decision to buy or not to in a heart beat , any hesitation, parts sold in a blink of a eye to another E9 owner
My family is lucky in away , we took a gamble 25yrs plus ago( when we did not own a E9) and purchased certain parts from Csl , csi csa cars that where being broken and we stored them away for use on our cars that we own now.
We also know of certain retired x E9 owners who have certain parts stored away for sentimental reasons , and kept these parts after they had sold their cars , broken them due to rust eating the body away, etc etc
We have guys on this forum that collect Petric steering wheels , own 2,3,4 plus of them etc etc , but only own one E9.
Every one has their own personal interest in buying , certain E9 parts , nothing wrong with that