The idea that people only buy Android phones at the low end is not valid as many Android phones are more expensive and premium than the iPhone. The Note 3 is a good example of this.
Also, the argument that people are waiting for a bigger iPhone or whatever also holds very little water because it assumes iOS is superior, which is no longer true. In the past, the main reason for buying an iPhone or iPad was the smooth operating system and large app library. The newer versions of Android now match iOS in these areas, and surpass it in terms of features. It could definitely be argued that iOS is now well behind in many ways and shows no sign of catching up as iOS 7 was a mostly superficial upgrade that added very little in terms of functionality.