I buy the TSA locks off Magellen.com. They have ones that have a dot that turns from green to red if they've opened your luggage. I was under the impression they had to let you know when they open your luggage. Of the times they've opened my luggage, only once did I get notification they did that. It must be about 4-5 times they never replaced the lock on my luggage so I bought some large (about 6" long) colored rubber bands at an office store and put one end on my handle and the other around the harp? of the lock close to the body of the lock. They can still open the lock and the band isn't in the way and so far the locks have not been lost. The locks I buy are about $10-20 a piece and that can get expensive replacing them. I have never lost anything out of my luggage that was opened by TSA but have heard stories of stuff disappearing. I NEVER check electronics, meds, jewlery (I don't travel with any anyway), or other things I don't want to lose.
I went to Aus back in 1990 with my son and it was a great trip! Enjoy.