Before a product gets a page, it has to pass one blunt test: overseas price divided by China price, in the same currency, should be about 2 or more. Below that, shipping, returns and fees eat everything.
Passing the number isn't enough. It still has to clear compliance — radios need an FCC ID, batteries need transport papers — and it has to look good up close on camera.
A lot of good products fail for a simple reason: the maker already sells them abroad, often at a price we couldn't beat. That's fine. If a brand is doing it well themselves, you should buy from them.
Some fail for less noble reasons. A concrete pen holder was an easy no.