Trusting Newegg and Aliexpress is part of the problem.
Also, if the price is too good to be true, it probably is fake. Look up what you want. Sort by review. Look at what the top-reviewed ones cost. Focus on the ones that have very high ratings (like 4.7/5 or better). Amazon will tell you if "customers usually keep this item" or "customers usually return this item". The lack thereof isn't a red flag, but a highly rated product that customers usually keep that costs a bit more than other products... there's probably a reason they're willing to pay more.