MANATEE — Existing home sales across Southwest Florida continued in June to flirt with paces not seen since the market’s historic balloon almost a decade ago.

The march has erased the area’s existing home supply to levels that traditionally signal a seller’s market. Although prices have yet to fully reflect that change, home values in Manatee and Sarasota continue to inch in the right direction.

Many agents now for the first time since the recession can’t meet buyer demand with the inventory available, a trend that could begin to work against the economy if it deters buying further.

Led by a climb in single-family transactions, Sarasota County reported 864 sales of all existing housing units last month, the second most since September 2005.

While Manatee’s numbers weren’t quite as strong in June, single-family homes are selling in Manatee at a rate 14 percent better than 2011, which had the best sales since the housing bust, according to figures released Thursday.

“We have had strong demand, and I don’t see a lot of new inventory coming on the market,” said Craig Cerreta, a Realtor with Sotheby’s International in Lakewood Ranch. “Probably the largest effect we will have is builders putting more projects out.”

Manatee County notched 265 existing single-family home sales in June, down slightly from the 270 in May but above last year’s pace by 26 percent, according to the Manatee Association of Realtors.

The surge in sales that’s built for much of the year has chopped inventory levels down to 4.7 months worth in Manatee, a stat that’s even lower once the multi-million dollar estates and bottom-dwellers are taken out of the mix.

Median prices in Manatee grew by 19 percent over the year to reach $178,000. The median is the midpoint; half the homes sold for more, half for less.

In Sarasota, there were 603 existing single family homes sold in June, a modest 2 percent rise from May and 18 percent jump from the same time last year, according to the Sarasota Association of Realtors.

Sarasota’s median sales prices fell during the month to $178,500, but that figure remains above the $175,000 median recorded in June 2011. Inventory in Sarasota has deflated to a decade-low of 4.1 months worth of supply at the current sales pace, with 3,816 total listings on the market last month.

“When the supply is low and the demand is high, prices will start to rise, but I don’t think we’ll see tremendous appreciation,” said Gloria Weed, managing broker of the Michael Saunders office in Lakewood Ranch. “It’s going to be a gradual growth.”

As that supply continues to shrink, prices will grow at a faster rate, restoring equity to area homeowners and opening the door to more traditional buyer-to-seller transactions, which have been limited by the overwhelming number of foreclosures and short sales.

Declining supply also should spark a resurgence in new home construction. The equilibrium between a buyer and seller’s market is historically about six month worth of existing properties, what developers like to see before building speculation homes. But if inventories fall too far, many experts believe it could actually work against the market by chasing investors and foreign buyers to other popular beach destinations like Tampa Bay or Fort Myers, where there’s still plenty to choose from.

“We’re all up against that,” said Marcus Vanzant, broker and owner of Marcus & Co. Realty in Bradenton. “There’s a lot of pent-up demand, and there’s not a lot of good listings. For the economy the way it is, the distressed housing is still out there, which is why prices are going up more.” Existing-home prices continued to show gains across the state in June but sales plateaued during the month as a shrinking supply of affordable homes kept buyers from the market.

Existing single-family home sales in Florida totaled 18,800 in June, relatively flat from May and up 5.3 percent compared to the year-ago figure, according to data released Thursday from Florida Realtors.

The statewide median sales price for single-family existing homes last month was $151,000, up 8.2 percent from June 2011. National home sales also saw a minor hiccup last month.

Total U.S. existing-home sales dropped 5.4 percent to a seasonally adjusted annual rate of 4.37 million units in June. That tally remains 4.5 percent higher than the level in June 2011, according to figured released Thursday by the National Association of Realtors.

The national median existing-home prices for all housing types was $189,400, up 7.9 percent from a year ago and the strongest monthly gain since February 2006.

Back-to-back monthly prices now have increased four months in a row from a year earlier — the first time that’s occurred since early 2006. That trend has driven largely by reduced inventories of underpriced foreclosures and short sales. Distressed homes accounted for one-fourth of June sales, unchanged from May but down from 30 percent the same time last year, records show.

The national average interest rate for a 30-year, conventional, fixed-rate mortgage fell to a record low 3.68 percent in June. The rate was 4.51 percent a year ago, according to Freddie Mac.

“We’re expecting inventory to hold around the six-month rate for the rest of the year,” NAR spokesman Walter Molony said. “That’s going to create balanced conditions, expect for shortages with the lower-priced properties, which are holding back first-time buyers.”

Josh Salman, Herald business writer, can be reached at 941-745-7095. Follow him on Twitter @JoshSalman