Domestic postcards cost $0.48 and international costs $1.45 (which is not any discount from 1oz letter, unlike domestic). They could also mail them from anothe

Domestic postcards cost $0.48 and international costs $1.45 (which is not any discount from 1oz letter, unlike domestic). They could also mail them from another country (which might also have cheaper print costs), especially since this is all first-class and there is no guarantee of delivery speed. For example, it looks like sending an airmail postcard from China is 5 CNY which is about $0.70, less than half the US rate. If you can find a printer there of equal or lesser cost, that's a huge savings. If you want to really stretch things, you can use surface mail (which USPS does not offer) for 3.50 CNY/$0.49 which is less than the cost to send it domestically within the US.