50USD... I can guess the quality...
An important thing about China, after a company launchs a new and good products lots of small "factories" try to copy. But always always always the just think how to break the market with cheap prices (if not they will not sell), so just produce rubbish. Later, after their market is bigger, even can produce cheaper than before changing the materials quality (even worst than before is possible). Every part has A, B, C.. quality. Later if they have problems about warrany with customers just need to change the name of their company and cheat more people again...
I think now, after some years on this, I even can write a book about the chinese bad quality
The Z802 was tested and it's really good at this moment.