SAN RAFAEL, CA - MAY 17:  Real estate agents arrive at a brokers tour showing a house for sale with a list price of $1.3 million May 17, 2007 in San Rafael, California. The San Francisco Bay Area has seen the median price for existing single family homes surge 6.6% to $720,000 while the national median home price dropped 0.9% to $215,300 in March. Marin County led the Bay Area surge with the median home price reaching a record high of $1,010,000, the first county in the state of California to surpass the million dollar mark.  (Photo by Justin Sullivan/Getty Images)
Justin Sullivan SAN RAFAEL, CA - MAY 17: Real estate agents arrive at a brokers tour showing a house for sale with a list price of $1.3 million May 17, 2007 in San Rafael, California. The San Francisco Bay Area has seen the median price for existing single family homes surge 6.6% to $720,000 while the national median home price dropped 0.9% to $215,300 in March. Marin County led the Bay Area surge with the median home price reaching a record high of $1,010,000, the first county in the state of California to surpass the million dollar mark. (Photo by Justin Sullivan/Getty Images)

The challenges facing prospective buyers of the least expensive homes in the U.S. are getting harder to overcome, says Bloomberg/Businessweek reporters Michelle Jamrisko and Alexis Leondis.

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