Consumers in U.S. make case for low-cost iPhone demand w/ increased sales of previous generation iPhones

New numbers out today from research firm Consumer Intelligence Research Partners (via AllthingsD) show that consumers in the U.S. are purchasing an increasing number of previous generation iPhones compared to recent years. It certainly helps make the case for a much rumored lower-cost iPhone, with the iPhone 4 capturing 18 percent of iPhones sold in the US during the June quarter, and the iPhone 4S an impressive 30 percent.

As noted by AllThingsD, the 52 percent of total iPhone sales captured by the iPhone 5 is much less than the iPhone 4S had just nine months into its release:

Nine months after the iPhone 5′s debut, it accounts for about half of all iPhone sales. The 4S still accounted for nearly three-quarters of iPhone sales almost a year after its launch.

While the obvious conclusion to draw from the data is an increased demand for a lower priced iPhone, CIRP’s Josh Lowitz thinks Apple could continue to take on the lower price market in the US with its previous generations of iPhones:

“We don’t see the need for other lower priced iPhones in the U.S.,” Lowitz said. “The legacy iPhones at reduced prices are selling well and doing an outstanding job of introducing new customers to the iPhone and Apple ecosystem. While 55 percent of iPhone 5 buyers already owned an iPhone, only 30 percent of iPhone 4S buyers and 22 percent of iPhone 4 buyers were prior iPhone owners.”

That of course doesn’t take into account the much higher trade-in value of the iPhone 5 compared to previous generations, which almost always makes the latest generation iPhone a better buy for most consumers.

Although several rumors have shared details and alleged spy shots of Apple’s much rumored lower-cost, plastic iPhone, it’s unclear if Apple would target only emerging markets with the device, or make it available everywhere it sells iPhones currently.