This wagon reached $9000 just now at the Mecum auction in Florida. No mention of the mileage, but, from the photos, it looks showroom. I don't know if it sold for that because, while the web video showed "sold," the auctioneer did not declare it sold. They kept asking for the owner to come to the podium, presumably to make the decision about lifting the reserve, but they never said that he did. Eventually they'll update the website with sold or didn't meet reserve information. I'll update this thread when they do.
What a nice car. Looks new. Based on what some of those similar Buicks have went for on BAT recently, this is a good deal at 9k if it sold.
It did sell, but the price was $13,200. Still seems like a good price for what looks, as you say, a nearly new car. The mileage isn't mentioned, and they don't show a photo of the dash. I'm guessing that, if it was very low, they would say so. Perhaps it's a very well maintained higher-mileage (50 to 100K?) car.