Fantastic Four #39 - #40 Question

I am trying to make a deal with a person to buy FF #39 and #40 in CGC 8.5. He want $675 for #39 and $485 for #40. He is willing to give me a 10% discount if I buy both issues, which would result in a total of $1,044. I mentioned that these prices seemed a little high. According to GPA, the last sale of FF #39 CGC 8.5 was $456, which occurred in November, 2021. Also, according to GPA, the last sale of FF #40 CGC 8.5 was $336, which occurred in October, 2021. I told that I would be willing to

Here are the sales of an FF #39 CGC 8.5 since January, 2020: 03/13/2020 - $250, 07/28/2020 - $331, 12/25/2020 - $425, 07/25/2021 - $432, 11/14/2021 - $456. It's clear that this book in grade 8.5 doesn't change hands very often. Here are the comparable books currently on Ebay: FF #39 8.5 (the book I am looking at) https://www.ebay.com/itm/274947023430?hash=item40041ea246:g:P38AAOSwv3FhQSC3 FF #39 PGX 8.0 https://www.ebay.com/itm/274225362199?hash=item3fd91af517:g:G0wAAOSwpr