NEW YORK ( TheStreet) -- If you're in the market for an iPhone 5 but don't want to commit to a carrier, you're in luck. Apple ( AAPL) has just started offering their new smartphones as "unlocked" devices to U.S. customers. That's the good news. The downside is you'll pay a premium for the privilege. Apple is asking $649 for an off-contract, unlocked iPhone 5 with 16 GB of built-in storage. The unlocked 32 GB model is $749. The 64 GB handset is selling for, gulp, $849. "Unlocked" means you buy the phone outright and then sign up for the GSM carrier's service you prefer (that means AT&T ( T) or T-Mobile). Unlocked iPhone 5s won't work on CDMA networks ( Verizon ( VZ), Sprint ( S), et al.). Unlocked phones don't come loaded with specific carriers' "bloatware" programs. They usually run the operating system and core apps that the manufacturer offers. Unlocked phones should be able to be used on most cellular networks around the world. The unlocked iPhone 5 will run on AT&T's LTE network, but maybe not other 4G networks. Apple's big, new desktop computers are also available beginning today. The redesigned iMacs are available with a 21-inch model starting at $1,299 and 27-inch configurations from $1,799. You can learn more online or in Apple stores. --Written by Gary Krakow in New York. >To submit a news tip, send an email to: email@example.com.