Collectibles store Collectors Cache has sold a PSA 10 graded copy of Ishihara GX for $50,000.
This card is extremely rare, only given out to The Pokémon Company International employees at TPCi President Tsunekazu Ishihara his 60th birthday. Last year a PSA 9 copy sold by Collectors Cache too, that one sold for $12,900 in April 2019. These promo cards are not meant to be sold to the public.
Information from Collectors Cache:
"This card was distributed personally by Mr. Ishihara himself to employees at Pokemon at his 60th birthday party. From what we've been told, only 30-60 of these cards are in existence however nearly none are available on the market since Pokemon employees cannot sell this card. Own an extremely limited MEGA RARE true piece of Pokemon history."
Some more background information about the card illustration, by the illustrator of the card Mike Cressy posted on his blog on February 8, 2018. It got removed but we still have this information from last year.
You can check the eBay listing for yourself:
Video from Collectors Cache: