The "vast majority" of markets do NOT require $300,000 or more for a modest single-family house. I couldn't find the info for new construction, but here's the lowdown on existing homes (which are more likely to be "modest" anyway):
Single-family home sales increased 1.9 percent to a record seasonally adjusted annual rate of 6.35 million in August from 6.23 million in June, and were 6.9 percent above the 5.94 million-unit level in August 2004. The median single-family home price was $219,400 in August, up 16.2 percent from a year ago.
Regionally, total existing-home sales in the West rose 5.6 percent to a pace of 1.69 million units in August, and were 8.3 percent higher than August 2004. The median existing-home price in the West was $322,000, up 20.1 percent from a year ago.
Existing-home sales in the Midwest increased 1.9 percent to a record annual sales rate of 1.64 million in August, and were 6.5 percent higher than a year earlier. The median price in the Midwest was $176,000, which was 11.4 percent higher than August 2004.
Total existing-home sales in the Northeast rose 1.7 percent to an annual pace of 1.21 million in August, and were 8.0 percent above August 2004. The median price in the Northeast was $254,000, up 16.5 percent from a year ago.
Existing-home sales in the South slipped 0.4 in August to a level of 2.74 million, but were 7.5 percent higher than a year earlier. The median price in the South was $189,000, up 9.9 percent from August 2004.
http://www.realtor.org/publicaffairsweb.nsf/Pages/EHS0905