As parts available on ebay and aliexpress from Chinese market are cheap but mostly they are B/C class, through they are good for hobby work but not for professional projects, i was looking at LoRa module at AliExpress its available for $4.5 but same moduels is priced at $19 on digikey/mouser that sounds really crazy, same is the case with ESP, on aliexpress i can found around $3 but on digikey it was listed $14
One of my friend told me as parts available on ebay/aliexpress are B/C grade their performance is inconsistent for example different range for same module. I want to know is there some supplier/web site from China where i can buy A grade items at reasonable price?