I have only purchased one audio component from China, and it took around 15 days to arrive at my door. As far as your item being chosen randomly for inspection by customs, that only takes minutes to open and tape back. I know this firsthand. We are not talking about a live animal that needs to be quarantined here!
A BIG CLUE is that the seller would not know that the item was randomly picked for inspection, unless he was watching via a remote camera in China! A customs agent would not even give a random caller the time of day, and that's if the caller knew the number to call, as well as the agent involved!
You have good reason to be skeptical.
If you are indeed getting scammed, you will never get your $ back from the seller. Your best course of action would be to have your credit card company reverse the charge. I hope you didn’t pay via another method. Best of luck!