I haven't taken the time to research this, but I got a message from a seller on eBay that I bought a coin from: This seems like a big deal...
Sounds like a bit of exaggeration - yes, USPS prices are going up on 27th Jan, but certainly not doubling. For example, a quick check on their website suggests an Express Mail International flat rate envelope to Australia will rise from $38.00 to $44.95, and a Priority Mail flat rate box to Australia will rise from $16.95 to $23.95. As an aside, the USPS lost $15.9 billion last year, which is no doubt related to these price increases.