As one who was adopted, I would suggest that you really, really think over your motives. I was adopted at the age of four by one couple and then, about six months later, I was "unadopted". I was immediately adopted by another couple and that adoption lasted until their deaths. However, up until shortly before her death my mother was still introducing me to everyone as "my adopted daughter." I was over 50 and, I've got to tell you; that, plus the 45 years of "you should be grateful we adopted you," was 50 years too much.
I am also not against foreign adoptions, but when you consider the number of children in this country who live in miserable situations and need help, why don't you consider one of them.
Also, this may be a disruption for your children that they will not tolerate easily. You might consider becoming a foster parent before you actually adopt. Having a strange child in your home on a temporary basis could alert you to what problems might arise if you adopt.