I sold Mad Max for $1000. He was a goliath though, and one of the 'first' ones to be grown to that size after we as a community started to know what we were doing with these fish. He was something of a celebrity on this site.
That being said, I think that anyone who has ANY atf over 12" has accomplished something very, very special. I happen to know that this TATF that Alan is selling is about three years old and absolutely flawless. It is a special fish, and worthy of a four figure price tag. That fish was from the second-ever confirmed import of TATF. It has history to it and is a special fish.
Yes, from time to time, larger 8-12" ATF show up, but mostly FATF or VATF. For some reason, I never see ATF for sale that are over 12". I suppose that is because either the owners keep them or they die.
Regardless, if Al was to sell this fish, I'd hope that he'd ask a ridiculous price and wait for the RIGHT owner to show up. IMO, the type of person who could properly take care of this fish wouldn't balk at a $1000 price tag for it. Part of the reason I asked so much money for Max was because I didn't want to sell him to a 15 year old who would plop him into a 90 gallon. I knew I could sell him for $1000, the only thing that surprised me was how quickly it happened.
There's a lot more to a fish's value than just how big it is IMO. Condition means a lot. Quality over quantity, and it is damn hard to beat the quality of the fish in question.