Meta.com is a 7-8 figure domain in this market. This year metaverse.io sold for $175k and meta.so sold for $149k.
I agree on your assessment that it would likely have been 7 figures. 8 if they knew it was Facebook.
For reference, I have bought/sold ZipX.com, Pedal.com, Shotput.com, etc
Except for used cars, real estate, bonds and stocks... every other asset is "bought and not sold" these days.
Sellers of an asset which is not in the list above don't even have a platform to tell the world that they are selling that particular thing.