I did vendor evaluations in the PRC for several years for industrial parts and supplies. IME a company like Shimano would have QA/QC staff on site or a long relationship with the manufacturer and things things go well. The difficulty is two fold, first I found the Chinese view a person who buys a "pig in a poke" is foolish and the seller clever. Second is end runs and fakes. After filling a contract for 10,000 chains to Shimano and the QA/QC is gone and they have materials left over the end run can be good quality until something runs out and is replaced, the good chain lube Shimano specified you don't remove from there chains until service is required is replace with crap you should remove day one or maybe just the Shimano blue dye is replace with a lighter color. So I would never buy a set of Shimano brakes at a bargain price from AliExpress but you might take a chance on a saddle.