Hi Annata,
Great question. I see from your profile that you have been educated in Europe, where governments heavily subsidize university education. You have obviously checked out some American universities and are concerned about the price. Before you make any choices, I would suggest that you examine your potential to get a free ride from a good American graduate school. The more prestigious the university, generally speaking, the larger the endowment and the more opportunities there are for fellowships, teaching assistantships, research assistantships and tuition waivers. I've always thought that while you may have to pay for undergraduate work in the US, if you can put together a strong set of credentials, you can get your Ph.D. free and also get a stipend for living expenses. For profit schools are less likely to offer fellowships or scholarships. Online programs are less likely to offer scholarships. Besides, you already have a very good MBA, so for you the next logical step is to a research university that is making significant contributions to the world dialogue about economics. That's the kind of doctorate you deserve and that will help you reach your goals. While online education may eventually allow students to participate in important research and learn from top experts, at this time I doubt you can find an online equivalent of the kind of economics program that is offered by a top research university.