For components, some of my experiences for outsiders:
1. For branded chips buy only highly specific ones, like mcu, ram. Avoid buying generic chip like opamp or regulator. They could be remarked or refurbished. Never believe factory package. They have their own refurbish machine and repackaging line.
2. If you need small quantity of components ask price for whole reel first, then tell them you want sample "yang-pin". The price shall rise to about 1.6-1.8x of the whole sale price. Most of the times it is still a lot cheaper than digikey.
3. Make sure to find shops having existing stock in the counter. Never let the runner "fetch from office". All gimmicks start from there.
4. Happy shopping