I am trying to work out packaging myself and am going to do some research online, searching ‘shipping fondant/gumpaste pieces’ and will also search shipping fragile items.
Here in Canada we can usually buy bubble wrap at some of our postal outlets, as well as big box stores (usually where you can buy envelopes & other shipping supplies). I’m not sure where you are, but I am sure there are a ton of places you could buy bubble wrap (or even shipping peanuts) online if you can’t find any locally.
I am going to do at least one, if not a few test runs with shipping fondant/gumpaste toppers, just to see how they hold up. Someone offered a great suggestion to use silica packs (or some sort of a dessicant) to help with any moisture so that the pieces do not soften during shipping.
Good luck! Hopefully someone who has some experience with shipping can give you some clear answers. :)