Whether you should go to get an MA in economics depends heavily upon what you intend to do after school. If your ultimate goal is to go into academia, an econ MA will not suffice. If, on the other hand, you want to go to the private sector, then an econ MA might be a good option.
I would also strongly disagree that you need to go abroad to get an econ MA that prepares you for graduate school. That may be true in general, but Duke's MA econ program is an excellent option for someone preparing for grad school. They have a lot of flexibility there, allowing you to take MA and PhD level classes in math, stats, and econ, so you can really fortify some of the weaknesses of your application, if a PhD is your goal.
If the MA degree is your terminal degree, then Duke's program is still a good choice, but others might be better, depending on what you're interested in learning and accomplishing.