In the last three months, Mr. Newport said, the lowest tier has been rising in value more than twice as fast as the other two categories. For the least expensive homes, “prices just shot up too fast on the way up and then went down more sharply,” he said. “We’re seeing the correction from that.”

The price cutoffs for each tier vary widely depending on the city. The cutoff for the lowest tier ranges from $86,000 in Atlanta to $349,000 in San Francisco.

Other data supports the trend. According to a report from Zillow, a real estate Web site that divides homes into three price groups, the gap in price changes between the top and the bottom of the market is narrowing. “It’s less that the top tier is cooling than that the bottom tier is strengthening,” said Stan Humphries, chief economist at Zillow. “The bulk of the recovery is due to the changes in the bottom and middle tiers.”

Even in Las Vegas, where housing prices are still slightly down over the last year, lower-end homes have ticked up in value, which may be good news for sellers but can be a hurdle for buyers. Mark Graham, a youth pastor who has been looking for a house for his family there for months, said buying a home for less than $150,000 could be a challenge.

“Houses are going on the market and within a day have multiple offers already on them,” Mr. Graham said, adding that most of the offers were from investors who did not need financing. “It’s more or less a heartbreaking market, because you get your heart set on a house, and then someone walks in with cash.”