I tend to have the opposite effect here - I sell games and DVDs yet all of my items are sent as large letter* and never go missing, yet if I dare buy something on eBay, odds on it will magically not turn up, even with Parcel Post! The most annoying part of this is when the tracking page says "delivered" with the location on the page being a different suburb (e.g. a post office/mail centre), and when you go there they say they don't even have anything of yours, or even tell you to check your local post office, which of course doesn't have it either - obviously the parcel must have magically turned into dust just like the rest.

[*] I offer standard postage (large letter) as well as Registered Post (signature), Parcel Post (tracking), and Parcel Post with signature (I haven't bothered with Express Post yet). Of course, everyone chooses the cheapest option. The only time I do not offer standard postage is when items don't fit in the letter gauge - such as video tapes, game cartridges and consoles/accessories. All items are posted in a padded envelope/bubble mailer unless they are too big.