extremely valuable antiques?

china still has a lot.

i doubt tough the inspectors would allow it to be smuggled out of the country.

Maybe China and Egypt. Well, since they're the countries that have the earliest civilizations in human history, you might want to contact some friends over there. good luck. ^^

you don't look for the country, you look for the company which made it. And you have to learn all that, no shortcuts.
In addition somebody told me that many thriftstores pay somebody knowledgable to sort through the things they think may be valuable, so it's not very common that you can discover something really valuable for pennies. Though it's going to be cheaper at a thriftstore than somewhere else, but I doubt you can make a lot of money be reselling underpriced thrift store items.