UPDATE [Wednesday, January 11, 2012 at 5:35am ET]: Bloomberg reports that Apple confirmed the acquisition, whose cost the company wouldn’t disclose.

Last week’s big Apple rumor was Apple’s purported talks to purchase an Israeli flash memory firm called Anobit. Now, Israeli news website Calcalist reports that the rumored deal is finalized. Anobit’s purchase price is still up in the air, but the report is calling for a dollar amount between $400 million and $500 million dollars, likely making Anobit Apple’s most expensive acquisition thus far. Anobit would come first ahead of NeXT ($400+ million), the company Apple co-founder Steve Jobs launched after being ousted from Apple.

Update: From the official Twitter account of the Israeli Prime Minister:

It is unclear if this tweet from the Prime Minister’s office is confirmation of Apple’s entry into Israel or if it was tweeted in response to the news report.

Anobit’s executive team, comprised of Chairman and CEO Ehud Weinstein, President Ariel Maislos, and more, reportedly informed their employees that the deal was finalized. Anobit’s campus is located in Herzliya, a major sector of Israel known for the technology that has grown from it. Perhaps just as exciting as Apple’s investment in new flash-based memory technology is Apple’s purchase in Israel: an Apple research and development facility in the country known for technological breakthroughs, such as its early work in mobile phones and instant messaging.

According to our sources, Anobit’s executive squad has not been formally introduced as Apple employees. However, if Calcalist’s report proves accurate, that should happen sometime soon. Something else to consider is if Apple chooses to formally announce the acquisition. For example, Apple bought a 3D-mapping company called C3 Technologies earlier this year, but it never announced the acquisition.

Anobit offered a fancy explanation of their technology:

Anobit is the developer behind flash-based memory that is typically more reliable, faster, and better performing than the flash-based memory that is accustomed in the current market. Flash-based memory is extremely important for Apple, as it is the storage technology found in iOS devices like iPads, iPhones, iPods, and Apple TVs. However, perhaps more important is that flash storage technology is moving to the Macs – for example, the latest line of MacBook Airs.