Having owned both Westone 4R and Shure SE535, flagship universal fit earphones, I can seriously say that the Klipsch Image S4i's are definitely worth the money, priced at <$100. The S4i's were my intro into the world of high end audio. If you're into bass, the S4i's provide a great amount of it; though I do not own the S4i's at the moment I can't speak much about the other frequencies as I can't remember, however the bass is controlled enough so that the overall sound is not muddied or overwhelmed by bass.
The most important factor, in my opinion regarding the S4i's is that they are comfortable. I do not like any of the stock tips that come with the 4R and SE535 and so I would have to buy foam Comply tips, which can add up to a lot of money since they don't last very long. The S4i's stock silicone tips are my favourite tips for my small ear shape. If anything, Klipsch should sell their 'patented' eartips for other earphones.
Oh and, S4i is the iPhone version of the S4.