I enjoyed this article about Chi-Fi from at The Verge:
The factories that make the drivers don’t care who they sell to; they maintain a certain level of quality because their clients depend on that. And once you’ve sourced the parts, it’s not expensive at all to put them together. “If you have a van and a bottle of glue,” Klasco says, “you can be in the business.”
I am a happy customer of one of the oldest Chi-Fi brands, HifiMan, which makes planar magnetic headphones at super low prices. Well, their prices are low for what types of products they sell, but in real dollar terms, they are pretty high: HifiMan mostly sell multi-hundred-dollar headphones, not $25 AirPods rip-offs.
I avoid most other Chi-Fi brands, because I would be concerned that build quality, and therefore produce longevity, would be very low. That said, I have paid lots of money for headphones from well-known, well-regarded, non-Chinese brands, and had them break in under two years.