PALM HARBOR - East Lake Woodlands may be the Tampa Bay area's most in-demand shopping center.

But its small shopkeepers wonder whether that's really a good thing.

This Publix-anchored plaza in a busy neck of Palm Harbor has changed hands twice in as many years. First, a Boca Raton-based investment group called Woolbright Development bought it for $16.25 million in August 2005. Barely more than a year later a huge, Houston-based, real estate investment trust, Weingarten Realty Investors, paid a seemingly astronomical $28.8 million for it, Pinellas County property records show.

That's such a huge increase over a one-year period that some local real estate officials wonder whether county records are mistaken or missing part of the story. However, a Weingarten executive confirmed its purchase price this week.

Whatever the true price was, small shopkeepers there say they are being hammered by rent and property taxes that have spiraled upward in the past couple of years.

Across the Bay area, real estate executives and shopkeepers report a similar cycle of buying and selling that is at least part of the reason for skyrocketing property taxes and rent. Investment companies including big real estate investment trusts, or REITs, and companies that use pension fund money are paying record prices for shopping centers, particularly Publix-anchored centers, and passing the related costs on to tenants.

Reni Myers, owner of a small pet supply store at East Lake Woodlands called Bo's Pets, saw her rent jump 25 percent recently. She hasn't yet received her annual common area maintenance "readjustment" bill - an annual bill from the landlord that factors in jumps in property taxes and facilities maintenance costs.

"I'm afraid to think what it might be," she said of the bill.

Investors aren't the only factor in the rising cost of doing business at shopping plazas.

Simple supply and demand also are huge issues. There isn't enough retail space for all the shops and restaurants that want it. That is driving up rent across the Bay area, said Pat Duffy, president of the real estate firm Colliers Arnold. Meanwhile, insurance rates are soaring but aren't directly tied to property values, insurance brokers say.

But the huge premiums investors are willing to pay for shopping centers is at least helping boost costs, real estate brokers and tenants say.

Historically the best shopping centers in the Bay area would fetch up to $180 per square foot, Duffy said. So, an investor might have paid $18 million for a strong 100,000-square-foot shopping center.

In recent years, investors have begun paying up to $250 per square foot for the best retail plaza, he said. So, that same 100,000-square-foot center might now run $25 million. Low interest rates are helping to make the big purchases possible.

"There's no doubt that Publix shopping centers command a premium, and the desire for shopping centers in Florida in general has been at a feverish pace over the last year," said Greg Lotzar, vice president/associate director of leasing for Weingarten Realty Investors.

Just a few of the sales are:

•Colony Crossings. This Publix-anchored center on West Hillsborough Avenue sold for $15.6 million in January 2006. Three years earlier, it had fetched only $10.5 million.

The center's "taxable value," or its value for tax purposes, shot up to $13.97 million last year from $10.82 million a year earlier, an increase of 29 percent. Julius Szabo, a manager of property owner Colony Crossing SDM LLC, did not return calls.

•Tyrone Gardens. Seemingly, this Winn-Dixie-anchored center in St. Petersburg might not fetch a premium price. Winn-Dixie just exited bankruptcy protection and other tenants include low-price retailers Big Lots and Aaron Rents.

Still, New Plan Excel Realty Trust, a New York-based REIT, and St. Petersburg-based Sembler Co. combined to pay $19 million for the center in June. Its previous sale was for $12 million in February 2004.

Sembler President Craig Sher said Sembler paid so much partly because it may redevelop the property.

•Seabreeze Plaza. In late 2005, a Maryland-based REIT called Saul Centers paid $26.2 million for this Publix-anchored center in Palm Harbor. Its taxable value jumped to $22 million from $16 million in 2006. A Saul Centers executive did not return calls.

David Kowkabany has watched the cycle of buying and selling and its effect on his common area maintenance, or CAM, costs - a charge to tenants that often includes the cost of keeping up the property, and sometimes includes property taxes and insurance.

Kowkabany has operated a tae kwon do center at Colony Crossings since 1996. Back then, his bill for rent and CAM was about $3,000. Today, it's pushing $6,000. A former neighbor of Kowkabany, a florist called Buds, Blooms & Beyond, pulled out of Colony Crossings after three years. A nearby shopping center offered more space at a lower cost per square foot, said flower shop owner Mary Conte.

Shopkeepers know what the taxes and common area costs are when they sign a lease, Conte said, "but what you don't realize is that it's going to be sold and that when it's reassessed it goes from $20 million to $25 million."

Tim Wilmath, director of valuation for the Hillsborough County Property Appraiser's office, said shopping centers' taxable values don't necessarily move in step with recent sales prices. When a property sells for more than its taxable value on the tax rolls, the county appraiser will adjust its value upward.

Generally, properties are evaluated according to sales of similar properties in a geographic area. That's why property taxes go up even for centers that haven't been sold recently, he said.

With that in mind, some real estate professionals are calling for a government-mandated cap on property taxes, similar to Florida's Save our Homes constitutional cap, which limits residential tax increases to 3 percent a year.

In Bloomingdale, some small shopkeepers at the Publix-anchored Shoppes at Lithia say passers-by barely know they exist.

County restrictions, limit the number of names on a center's marquee sign along busy Lithia Pinecrest Road. Publix, Bank of America and UPS are on the sign; smaller tenants such as Nature's Health Foods aren't.

That's why Nature's Health Foods owner Lela Lilyquist is upset at the bill she got from her landlord, Inland Retail Real Estate Trust, in early 2005. It asked her to pay an additional $7,000 in property taxes within 30 days. She wonders whether the landlord's purchase of the center in late 2003, for $12.8 million, contributed to her expenses. "I'm thinking that when they overpay for these shopping centers, it's passed on to the tenants," Lilyquist said.

A spokesman for Inland, Darryl Cater, said taxes did rise after Inland's purchase of Shoppes at Lithia. However, that was primarily because it was a new center, and Inland bought it from the original developer. Tenants' previous tax bills were for undeveloped land. Cater said taxes have been dropping there recently.