(Reuters) - Warren Buffett says he will not pay a penny more than the $72.50 a share he is already offering for ketchup maker H.J. Heinz Co , and after an initial hesitation, most investors seem to be taking him at his word. Buffett's Berkshire Hathaway Inc and the Brazilian private equity firm 3G Capital struck a deal Thursday to buy Heinz for $23.2 billion in cash. The legendary investor made clear in a CNBC interview on Thursday that the bid was his final offer. ...