High-end single-family home sales have dropped 10 percent from January through May. This Colonial-style dwelling featuring a gourmet kitchen in Hingham’s Kress Farm is currently available for $1.95 million.

Buyers of ultra-luxury homes in Massachusetts are finding the keys to some good deals.

Real estate brokers say the number of high-end homes available for sale has ballooned over the last year, putting buyers in a better bargaining position.

Sales of single-family homes priced $1.5 million and higher dropped 10 percent during the first five months of the year compared to a year ago. The drop-off has occurred as the supply of pricey properties shot up by as much as 20 percent.

“What we are seeing is a dramatic jump in inventory rather than a slowdown in sales,” said Mark Lippolt, executive vice president for Coldwell Banker Residential Brokerage Central New England.

Some 1,133 single-family homes with a price tag of $1.5 million or more were available for sale at the beginning of June, 22 percent more than a year earlier, according to statistics provided by the MLS Property Information Network, or MLS PIN.

There was almost a 16-month supply of million-dollar-plus homes available across Massachusetts at the end of May, compared to about 13 months’ worth of supply in May of last year, said Lippolt.

The number of unsold homes in even more moderate price ranges has increased. Listings for homes priced under $800,000 rose 59 percent as of June 1 compared to a year earlier, according to MLS PIN, while home listings in the $800,000 to just under $1.5 million range increased 38 percent.

The glut of for-sale homes has created the buyers’ minds a “lack of urgency,” said Lippolt.

“There’s no question that the excess of inventory does have an impact on the buyer and buyer mentality,” said Lippolt.

Lippolt said an ongoing concern in the real estate industry is whether the increase in available for-sale homes is being caused by serious sellers or homeowners who are simply testing the market.

“Is it a sign of people with a clear need to sell and a clear sense of urgency putting their homes on the market, or is this speculative selling by those who are looking to cash out at what they believe may be the top of the market?” he said.

A total of 327 single-family homes priced $1.5 million or higher were sold in Massachusetts from January through May, a 10 percent drop from the same period last year, according to The Warren Group, parent company of Banker & Tradesman.

In Weston – where the median selling price for a single-family home has exceeded $1 million for the last three years – the number of sold homes in that price category fell sharply. Only 10 homes priced at $1.5 million or more sold during the first five months of 2006, compared to 33 a year earlier, according to The Warren Group, which collects statistics from the registries of deeds in Massachusetts.

Sales of million-dollar-plus properties statewide have increased steadily over the last three years. In 2003, 635 single-family homes in the $1.5 million and above price range were sold. A year later, the number had grown 57 percent to 999 sales, and by last year the number had jumped to 1,111, according to The Warren Group.

Sellers have enjoyed a market where a limited supply of available homes meant faster sales and multiple offers. But real estate agents say there has been a significant shift in the luxury-home market.

“With so many properties on the market, it takes longer to sell,” said Carolyn Chodat, broker-owner of Classic Properties in Medway.

‘No Rhyme or Reason’

Homes listed for $3 million to just under $4 million were on the market an average of about seven months in January through May of this year compared to about 5.5 months during the same time frame in 2005, according to MLS PIN, while homes listed for $2.5 million to just under $3 million spent an average of 189 days on the market, compared to 178 days last year.

To attract purchase offers, real estate brokers have tried offering bonuses to selling agents or encouraging sellers to pick up closing costs. But the most effective strategy – even for very expensive homes – has been slashing prices, according to Realtors.

“What we’re beginning to see is that those incentives are not having as much of an impact as a basic price reduction,” Chodat said. High-end home purchasers are not “particularly interested in whether you’re going to pay the closing costs, or offering new carpeting,” Chodat said.

“The only way to encourage the market to move – to have any attrition of this 13-month supply – is by bringing down the prices,” she said.

Lippolt agreed that pricing is critical.

“The sellers need to be aware that they have to go into the market with a clear-cut pricing and clear-cut marketing strategy,” he said.

Two years ago it may have been possible to sell homes in the $1 million to $2 million range without a price adjustment. But today, if there hasn’t been much of a response to a property within two months, sellers and agents need to seriously consider a price adjustment – particularly if a homeowner is in a hurry to sell, Lippolt explained.

At the very high end of the market, supply has increased dramatically. At the end of May there were 34 homes priced $6 million or higher available for sale, Lippolt said, but only five homes in that price range sold in the prior year. That translates into 82 months of available inventory.

“There’s no rhyme or reason between supply and demand at the very high end,” he said.

Mary McCready, who manages the Hingham office of Jack Conway & Co., said there hasn’t been a “steady flow of sales” of homes priced $1.5 million and above.

“It’s been a volatile market,” said McCready.

McCready said buyers have more negotiating power. As a result, real estate brokers representing sellers are focusing more on making sure that a home is in tip-top shape to compete with other properties on the market.

Real estate agents are often meeting with sellers with the names and contact information of painters, roofing contractors and other professionals to assist sellers, McCready said.

“The goal when you meet with the seller on a listing presentation is to take the property to its highest possible level in terms of readiness for the market,” said McCready.

In Newton, Brookline and Wellesley – communities where million-dollar homes are plentiful – sales of single-family homes priced $1.5 million and higher have remained about the same this year. In Brookline, there were 19 such sales from January through May compared to 17 during the same period in 2005; in Newton, there were 25 compared to 26; and in Wellesley, there were 34 down from 38.

Meanwhile, on Nantucket, where multimillion-dollar vacation homes are almost a common sight, 42 homes priced $1.5 million or higher have been sold so far this year, up from 37 during the same months in 2005. One single-family home fetched $9.4 million in January, according to The Warren Group.