Their price seems to be all over the place. I think they were discontinued. Pretty sure I paid 12 USD for mine.....maybe 14...
Out of all the KZ iems, these seem to be among the more balanced, along with the ANV (which every seems to hate..I love em with my filter 'mod', otherwise they are just o.k.). They are laid back with a pretty large soundstage, at least compared to what I'm used to. I would put it almost on par with the VSD3(no s), but not quite. They always pick up more detail than I expect
They're are competent at everything, but don't really excel anywhere in particular; they're not overly bright, or super bassy, or have hyper aggro mid, or so analytical they sap the fun out of everything. They're not thin or thick sounding. In my opinion this makes them the perfect everyman's iem. Add to that good isolation (even though they are vented everywhere....no idea how it works but it does), comfort, and if you get them at the right time, a low price....they're pretty much my perfect iem.