With my COMC shipping back to AUS I just look at what I have saved over the duration since all the last purchases - if it costs me $3 postage within the US to COMC for an ebay purchase plus processing cost when some sellers would charge $14 or more or only use the global shipping program OR not ship to AUS then I figure I've saved $X on postage and depending on what I am keeping and selling I decide on which speed I send back at cost and go from there. It's been good so far!