For a 66+ here are the past auction prices for this coin
04/2014: $9400
02/2015: $9106
07/2015: $7344
10/2019: $5400
Average: $7812.50
PCGS Population: 5
Price Guide USD: $9000
I think your getting a good deal according to the average and the current price guide price but look at how low each auction price got from April 2014 to October 2019! It dropped since April 2014 $294 $1762 and finally $1944
From the $9400 to the $5400 it dropped $4k!
It's up to you but imo I would pass since the price for this specific coin has been dropping each year on auction and if you would buy it know who knows how much you can get for it when you resell it (if you do plan on it)
Good luck and let us know what you are doing