Replacement cables don't sell in anything remotely like the quantities that cheap IEMs sell in, so especially if they're a little nicer they're bound to be expensive compared to the cable included with the cheap IEM. (And I don't see anybody claiming that something like a Tripowin Zonie has magical audio properties.) Having said that I have no problem with the Salnotes Zero stock cable- snugging it up under my chin takes care of the (mild) microphonics.£19.99 cable for $20 IEM - wow nice deal!
$100 cable for $1000 speakers/studio montors - AUDIOFOOL! PURGE THAT HERETIC!