[mrreality68]

Originally Posted by STL1944

Having unique, high price items, would seem to draw eyes to the auction and have an "umbrella effect" of raising bids on other items.

This is one of the reasons some auction houses will discount or waive fees for high profile items.

Agreed. High profile cards card excitement for the auction. Increases the social media exposure and increases the number of visits to the sites. The buzz also on cards like those make main steam media and draws people to the sight that might not have gone and this helps bring new money.
However, the one thing I do not know and cannot quantify is how much more Money brought in and how it affects the overall bids.