I don't think it is worth it. I live in Romania and our GDP per capita is $12.575 and I don't consider it a good country to advertise online.
Why? Well, most of those middle countries will rather order from their country than outside of it. This is the case in my country, even my parents prefer to pay more here than order from outside just because it is easier for them.
I remember that my mom ordered a bracelet for $18 in my country and when I asked her why didn't she ordered it from AliExpress for $3 she said that it was easier for her due to native language customer support. (TRUE STORY)
This is also what happens in Turkey, Bulgaria and I believe Poland too. I don't know about other countries, but this might answer your question.
Don't get me wrong, it is possible. And you can make profit, but it is harder.