Last year I sold a Gina that was loaded with Ivory. I went to Nevada to ship it, and sent it via Priority Mail WITH NO INSURANCE! Why, you might ask did I do that? First of all I feel like putting a high dollar value on your cue is like putting a target on it, and I know from past experience that the chance of collecting several thousand dollars from the post office is almost nil, unless you can supply an original bill of sale, and that might not be enough. They might also want proof that specific cue was the one that was shipped. In other words you are screwed either way if the cue gets confiscated or stolen. IMO, it is more likely to happen if someone/anyone thinks there is something very valuable in that box. I have shipped several expensive cues that way and have yet to have a problem with any of them.
I did sell three high end cues late last year (Joss West, Tad and Prewitt) and shipped them via Fedex, mainly because the mail had become so unreliable and slow, thanks to our new postmaster and his main accomplice. What I've noticed already, after the first of the year our mail service has picked up again, back closer to normal delivery times.