Where I am, these types of phones are essentially useless because you'd have to buy a local sim, and to do that you'd need to show your id or passport, which defeats the purpose of the item itself. You mentioned that you can get an international card with the phones. Will you be able to provide that with the phone? How much credit will it have?
And will you do international shipping?
Most/many countries don't have laws where you have to have your passport or government-issued ID scanned before buying a SIM card.
Worst case you can bribe a hobo with a cold beverage to sign up for you with his own ID.
I'd be more worried about the phones not supporting one or more of the many cellular frequency ranges in different regions around the world.