Roidmi versions

Hi, there's been a heap of roidmi deals on ozbargain over the last year or so, so I'm hoping that some of you that have purchased can help me out.
From what I can tell, there is an 'original' and the updated 2S. The 2S seems to come in at least two versions - Chinese and international. However, I have also seen products described as 'original 2s', so aren't sure if these are yet another version.
What I am struggling with is the differences between the different versions as different vendors appear to use the same descriptions for different versions. Prices vary from around $15 to $50+ for what appears to be the same thing.
Has anyone that has bought a roidmi figured out how the different versions compare? Also, an I correct in concluding that to change the frequency I have to download an app that forces the use to create an account or login with their social media credentials?
Thanks in advance