Hot-selling iPhone 4S nearly gone from retailers

— -- If you came out empty-handed looking for that elusive iPhone 4S this weekend, you weren't alone.

Apple sold more than 4 million units of its new megahit iPhone in the first three days of sales. That's more than double the 1.7 million sold for the iPhone 4 at launch in 2010. Now, the phone is nearly gone at most retailers. And if you order online, you'll have to wait anywhere from one week until the end of the month.

"The iPhone is still the most in-demand device," says Charles Golvin, an analyst at Forrester Research. "Nothing even comes close."

On its website, Apple is offering one-to-two-week delivery for online orders. Customers can make reservations for next-day pickup at the stores, according to the site, but that option is only available online when the retail stores are closed.

Apple's blockbuster sales of its iPhone 4S came in part because many current customers were ready for an upgrade and the phone became available on three U.S. carriers, Golvin says. When the previous generation iPhone 4 launched, it was only available on AT&T.

Carriers who sell iPhones are promising long delivery times. AT&T says devices will be available within 21-28 days, while Verizon offers an Oct. 28 delivery date.

Sprint is out of stock of the 16 GB ($199 with contract) and 32 GB ($299 with contract) models, but does have the $399 (with contract) 64 GB model available.

The iPhone 4S is also being sold at some Best Buy, Target, Walmart, RadioShack stores and Apple resellers, but it was non-existent in spot calls to stores.

Every iPhone update since the device first launched in 2007 has seen a crush of interest. Long lines form in front of stores across the nation as phones sell out within a few days. That's usually followed by sporadic inventory in stores that feeds the buying rush. Eventually, the crowd of consumers get served within a few months of the release.

The buying cycle always plays out this way due to component constraints, "and they can only build so many at a time," says Gartner analyst Van Baker. "Did they (Apple) realize they would double the volume of iPhone 4? Probably not," Baker says.

Apple declined to comment.