I saw this posted on a Estate sale site. Sale going on now in New york. https://www.estatesales.net/NY/Little-Neck/11362/2409501
The sale is in New York. The car is located in New York. George Barris customized the car. They've got it worded oddly. Not George Barris's estate sale.
It doesn’t look like a typical Barris custom. I guess I would have expected more. I wonder what documentation they have. Maybe he just autographed it somewhere?
That listing doesn’t appear to be correct according to Autoseum’s website, who claims to have commissioned the build. According to this someone who learned the trade from Barris built the car for charity and Barris signed the dash. https://www.autoseum.org/2016/02/03/newsletter-1-october-2010/
I remember this Buick - it was a project GS that students worked on restoring. Barris signed it afterwords as mentioned above.