Has anyone yet been pulled aside and questioned? I don't recall hearing about it and I feel a big deal would have been made about it if it had happened.
Yeah, more than a decade ago. I declared a (roughly) $3,500 to $4,000 recommended retail Seiko Astron GPS watch (I can't recall exactly as it was that long ago) that I picked up new (uncompleted lay-by) for about $2,200 on the way out the country for a 10-day trip. I was warned on the way out.
I'd lusted after these watches for a long time, but couldn't really justify them, but Thomas's jewellers in Melbourne would have twice yearly clearances of typically hard to move gear as well as items that had been put on lay-by where the original buyer hadn't completed the lay-by. I could rationalise the roughly $1,200 discount.
I'd bought the watch already when I was asked to go overseas by my employer, and at that point I quickly did some research on what that specific model was selling for 2nd hand. Since it was a lay-by, it was already on the 2nd hand market as real watch nerds were upgrading - for under the magic threshold. Armed with some printouts of ebay ads, just in case, I claimed the GST on the way out - got warned it was over the threshold to bring it back in without declaring it and left on my work trip.
On the way back in, I didn't declare that I had goods over the limit, annoyingly couldn't get the auto-gates to work so had to go through a manual passport gate, got asked at the manual gate about the watch, said, yes, I'm bringing it back in, but it's only worth $750 now, the guy laughed and said "I've heard that one before" and I laughed and said "I'm sure you have, but here are some ads on ebay for the exact model number of the watch in question". He wrote a couple of letters on my passenger declaration and sent me on my way.
I'm not sure that anything would have happened if I had used an automated gate (or maybe that's why the gate didn't work), because I know that they don't have a screen when they review the incoming passenger declarations.
I probably shouldn't have bought it new if I'd thought about it - it turns out there's a good second-hand market for these, but I did get it with a five-year warranty.