The PMI ranking puts the New York area at No. 14 on a list of frothy places. But National City ranks the Big Apple at a mere 68 out of 299 metro areas -- below such places as Flint, Mich., and Duluth, Minn. National City isn't claiming that Flint is pricier than New York, of course, but says Flint appears more overvalued in terms of supply-and-demand fundamentals.Metropolitan area rankings.No national study can take into account all of the factors that affect house prices, or determine whether a particular home or neighborhood is dangerously overpriced or a screaming bargain. Such assessments require the expertise of people in the local market. But the rankings do highlight certain cities and regions where buyers may want to be more cautious than usual. That's particularly true in the cases where the studies agree: The PMI, National City and CSFB rankings differ markedly -- but all include the Riverside-San Bernardino, Calif., as an area ripe for a downward correction.