I currently have three Porsches (911, 912 and Boxster), two Sunbeams (Tiger and Alpine), and an Elva race car and my sons/daughter have an S2000, Type R and BRZ. I have had my 911 for over 35 years. Two points:
One, a Porsche is a Porsche for a reason. If you want the full Porsche effect, and the full experience that a Porsche offers, you want to do it right and not skimp on parts or tires, etc.
Two, I have found that there really is a difference between OEM and true factory parts. Sometimes it's just a little bit - like the part has been cleaned up and polished. But sometimes it is a difference in the overall quality and workings of the part. Yes, the prices are high from the dealer. But when there is a difference it is often worth it if you really want to have everything the car can offer (though not always).
Also, dealers do offer various discounts, including PCA and others. And the more they get to know you, the more they find discounts for you.
So I'm a full supporter of factory parts when possible.