For a guy worth billions of dollars, Donald Trump is actually kind of frugal -- at least when it comes to spending on his presidential campaign. His quarterly campaign finance report, filed Thursday with the Federal Election Committee, reveals the Republican frontrunner's presidential campaign spent $4.2 million from July through September. While that is three times the amount doled out the quarter before, it is still significantly less than a number of his rivals, including Ben Carson (who spent $14.2 million), Jeb Bush ($11.5 million) and Bernie Sanders ($11.3 million). Democratic frontrunner, Hillary Clinton, spent over six times more than...