A group of Argentinean investors paid $7.5 million for 15 condo units at the Artech Residences at Aventura.

The buyers paid $502,500, or $324 a square foot, for each unit on June 4, according to Miami-Dade County records. Even with the bulk buy, only 41 of the condos 235 units have been sold.

Prior to the bulk purchase, the average price of the units was $744,044, according to research by Bal Harbor-based Condo Vultures Realty.

The bulk buyers' average unit price was 32 percent less than that, but, "in a market like this, I'd say $500,000 per unit is high,” Condo Vultures principal Peter Zalewski said.

Adam Greenburg, the managing director of Miami-based Baybridge Real Estate Group, agreed that while the developer got a good deal, it wasn't as good for the buyer.

If the buyers plan to rent out the units, they paid too much, he said. However, he added that they might have been impressed with the amenities, which include an infinity pool, fitness center and spa, and concierge service.

The investors did not record a mortgage in Miami-Dade County to finance the deal, so it is likely they paid cash.

Artech was developed by the partnership of Fortune International and Shefaor Development.

Shefaor President and CEO Gilbert Benhamou said the bulk buyer plans to use some units as second homes and others as rentals. They were given a discount on Artech's normal price because they bought in bulk, he said.

Artech started closing units at between $600 and $700 a square foot, but has closed most of them at about $400 a square foot since the credit crunch made it difficult for buyers to get financing, Benhamou said.

"We are touching the bottom and things can only get better from now on,” he said.

The entities that bought the 15 units in Artech are: Bayview U.S. Properties, Giga Apartments, Golden Federal and Sorlib. In state records, they all have their address at 9130 S. Dadeland Blvd., Suite 1600, in Miami. Cesar Halpern, of Buenos Aires, Argentina, is listed as a manager for all four companies. Three of those companies also have Zulema De Halpern, Daniel Halpern and Mark I. Glanz, all of Buenos Aires, as managers.

Fortune International President Edgardo Defortuna is from Argentina.

This isn't the first bulk buy at Artech. In November, a company managed by four executives of Artech's construction lender, Chicago-based Corus Bank, bought four units for a combined $5.5 million – a price that many real estate experts said was high. Several months later, Corus (NASDAQ: CORS) was hit with several shareholder class action lawsuits that questioned whether that transaction caused a material misstatement or omission on its financial statements.

Corus, which made a $130 million mortgage to Artech's developer, reported that only $49 million of its South Florida condo loans were performing out of $955 million in condo loans here as of March 31.

Benhamou said the developers are working closely with Corus to achieve the highest price per square foot possible at Artech. Once they sell a few more units, they will have approval for Fannie Mae-backed loans.