If you are wondering the extent. Consider this.
1997-98 SPx Grand Finale (Stated Print Run of 50) have 50 cards in the set, total of 2500 in the wild. There currently aren't any for sale on eBay/COMC with only a handful (approximately 5-8) available on eBay in the entire year of 2020.
1996-97 Select Certified Mirror Golds (Stated Print Run of 24) have 120 cards in the set, total of 2880 supposedly in the wild. There are currently approximately 60 Total (36 different) available on COMC alone.
I've only seen one Gretzky Grand Finale ever, while there are (4) Gretzky 1996-97 Mirror Golds listed on eBay at this moment.
They are beautiful cards, but based on this, the prices that they are going for aren't justified. I'm guessing a lot of people are buying based on the Beckett stated print runs which are terribly off. This goes the same for a ton of other pinnacle inserts such as Epix Moment Emeralds.