Based on what I've read, and what Saban and his wife have said, I think there are several reasons he left Miami, and the possibility of a sale is pretty far down the list.
In order, here's why I think Saban left Miami:
1. He really does like the college game better.
2. He and his wife were not happy in Miami.
3. Miami isn't such a great place to raise a 15-year-old girl whose father is a major celebrity with all the trappings that go along with that.
4. He was 6-10 this year, and didn't think next year would be any better -- D is getting old, there's no QB (Culpepper is beaten to a pulp, has seen his best days, and didn't have Chris Carter or Randy Moss to throw to), and that probably wouldn't change next year. So it's true that he didn't finish the job he came to do in Miami, but it wouldn't be finished any time soon anyway.
4A. With all that, the possibility of a sale was out there.
5. There are very few college jobs that compare to Alabama, and they don't come open very often. Count 'em: Texas, Florida, FSU, the real USC, Ohio State, Michigan, Penn State, Notre Dame, Oklahoma, Nebraska. So if you have the chance, you take one when it's offered.
I'm under no illusions that Saban has any particular attachment to Alabama right now. It was one of a handful of college jobs that would have interested him, and it came open. For only the third time in 50 years, our timing was right -- Bryant, Bowden (which we ourselved botched) and Saban.
In time, if the administration plays it right and makes sure he gets left alone (and as long as Witt is there, they will), Saban will get the Crimson thing, and develop a real affection for the University.
The one college job I could see him leaving us for is Penn State. It's one of the few elite jobs, and it's close to home. And we all know how much of a draw "home" is. We'll need that affection when Paterno retires and Saban is offered that job.