Apple is continuing to produce millions of its iPhone 3GS device in spite of releasing the iPhone 4S just two months ago. According to sources cited by Digitimes, the Cupertino-based firm is on course to have manufactured 2 million iPhone 3GS units this quarter, with a reported 1.4-1.6 million planned for the first quarter of 2012.

While 3.5 million units over six months dwarfs the demand for the iPhone 4S — which could sell as many as 30 million this month alone, according to analysts — few other manufacturers would produce such volume of a device that has preceded by two newer models, particularly as Android’s range and popularity continues to grow.

Speculation has regularly linked the company with the introduction of a ‘Nano’ style, more affordable device, but rather than compromise on quality, Apple leverages its product range to offer older devices, or models with less memory, to consumers at lower prices.

It isn’t impossible that Apple might introduce a lower-range, Nano device at some point — it could do incredibly well in developing markets — but for now production numbers suggest it is happy to let its tail of devices offer customers a more affordable choice.

The device remains popular with customers as it supports Apple’s latest operating system, iOS 5, to give a quality experience at a lower cost. Rumour has it that the 3GS will be discontinued next year, and Apple is already selling reduced rate iPhone 4 devices and other models with lower capacity to provide less expensive options for consumers.