Has anyone used Post International Express Envelopes C5 to send coins internationally? It has a disclaimer that you have to sign to say it is only documents.....but i have used the domestic version to send them fine. Internationally i am a bit iffy about it.
I dont know the C5 price but the 500g bags marked for OS I think are around $24 to get it to US with tracking.
There are others here with more experience posting overseas who may have a better/cheaper method. Only time I did it bag was near maxed in weight on a non PM item but for the tracking option and the value of item it was worth it.