Apple is now selling unlocked versions of its iPhone 5 smartphone, which means instead of choosing from carriers such as Sprint, AT&T, and Verizon, those willing to shell out at the Apple Store can get their hands on the device contract free.

The unlocked phone gives users the ability to insert nano-SIM cards from any supported network rather than be locked into a multi-year contract.

However, the phone isn't cheap. The 16GB version costs $649, compared to $199 for a typical contract model, and goes up to $849 for the 64GB model.

"The unlocked iPhone includes all the features of iPhone but without a wireless contract commitment," Apple says on its website. "If you don't want a multiyear service contract, or if you prefer to use a local carrier when traveling abroad, the unlocked iPhone is the best choice."

The iPhone 5 is undoubtedly one of the most desired smartphones on the market. It features a brilliant 4-inch retina display, an updated 1.3GHZ dual-core Apple A6 processor, 1GB RAM and Apple's updated iOS 6 operating system.

However, the handset faces stiff competition from other similar spec'd devices which cost far less.

Google's LG Nexus 4 offers a quad-core processor, Android Jelly Bean and 2GB RAM and starts at $299 for the 8GB model and $349 for the 16GB top-end variant.

Or you can opt for the top selling smartphone in the world - Samsung's Galaxy SIII. That phone features a 1.4GHZ quad-core Cortex-A9 processor, 1GB RAM and a larger 4.8-inch 1280x720 HD display at 306ppi. The starting price for a 16GB model, SIM-free is around $500 - almost $150 less than the iPhone 5.

Finally, if neither Android nor iOS 6 takes your fancy, you can buy Nokia's flagship Windows Phone 8 smartphone - the Lumia 920 - which also starts at around $500 unlocked and without a contract.

The Lumia has a 1.5GHZ dual-core processor built by Qualcomm, 1GB memory and has a 4.5-inch 1280x768 WXGA capacitive touchscreen at 332ppi.

The big question is, with such fierce competition, can the iPhone continue to compete at such a high price point?

Apple is offering every unlocked iPhone 5 with 90 days of free telephone technical support and a one-year limited warranty.