 This is a Bloomberg Money Minute. Just two weeks after the Boston Celtics won it all. Banner number 18 has been secured. The Celtics are NBA champions. The team is being put up for sale, valued at more than $5 billion. In just the past year, three other NBA franchises in Phoenix, Charlotte, and Dallas were also sold, each for more than $3 billion, as deep-pocketed investors see teams as solid investments.