"Maybe this shows that people are jumping ship from AT&T," said Scarsella.

While prices may continue to slide in the short term -- historically, prices have dropped 20% to 25% once the specifics are known of the next iPhone -- they will level off in the next 30 to 60 days, said Scarsella.

"The iPhone 4 and 4S are in high demand, especially the iPhone 4S," Scarsella said. Foreign markets are particularly eager to get their hands on those two models. There, carriers do not subsidize phone purchases, so consumers must pay full price, Instead of being locked into a contract, they buy pre-paid mobile minutes.

On Friday, shortly after midnight PT, Apple and the three iPhone carriers in the U.S. -- AT&T, Sprint and Verizon -- will begin taking pre-sales orders for the iPhone 5.

The reduced-price iPhone 4S and iPhone 4 are available now at $99 and for free, respectively, at Apple's website.