it depends on how much of a whiner you are ^_^. improvements are usually very subtle, but if they are what you needed to stop complaining then it's worth it no? that's pretty much how I roll so like you would guess it's totally mood dependent. I can very well enjoy a 30$ IEM into a clip+ one day, and be fed up with my jh13 into a portable amp the next.
2 things I know now are that comfort and durability are not factored into pricing, and that making up a ludicrous price is enough to convince a lot of people that it is the best.
-still I usually have little to complain about IEMs in the 300 to 600$ range.
-then I put cheap stuff into 2 main categories, it's a caricature but mostly that's what I think: one with big ass bass to impress and hide the misery of the mids and trebles. and the neutral/detailed ones with sibilance and/or harsh distortions.
-when 600$+ is often a hit or miss for me. I hear some nice technical qualities most of the times , but the signatures are often too pushy for my tastes, like they try to show too much for their own good, how unique they are. so you end up living the dream if that's what you really wished for, but mostly you try to get used to something not for you because you're telling yourself that it is what quality sounds like.
ok now I'm depressed. I will now go and try to kill myself from eating too much sour cream and onion pringles. and wondering what all the flavors unavailable in my country taste like.