I'd be super cautious. Sometimes we will lose entire boxes of angelfish upon arrival from Asia. Most of the time, we will lose nearly a quarter of them within a few days, some weeks we lose many more. Another big issue is, when dealing with bulk angelfish, discus or other SA cichlids you are chancing an outbreak of discus or angelfish disease, which is extremely contagious and easily transfers to other tanks from water changes and infects all fish in the tank. The disease is almost always fatal, and at many stores will wipe out most of their angelfish.
I wouldn't order angelfish from overseas because of the huge risk. I would definitely recommend finding breeders and buying angels from them instead since they are just about always healthier. However, if the angels you want, can only come out of Asia, just try to be as prepared as possible for possible outbreaks. As for the disease, I am unsure as to how to treat it. I do know that you would need to use a couple of different medications all together though.