My understanding, and please let me know if these are wrong
1. You wish to become a General Manager in a mid size social firm, "not necessarily in Asia"
2. You are reluctant about going down the lane called GMAT.
3. You believe that post a costly MBA, you would spend a lot of time taking away the debt from your head, which may result in working for money rather than working for satisfaction.
Why not compromise with a good b school?
There are cases where one doesn't need a B School education to prove the might - cases such as Steve Jobs, Rajiv Suri and a lot many. However, are these opportunities abundant? Yes, if you look in the right direction at the right time with the right mind and with a lot of play from the planets and stars, I suppose. However, a good education, unfortunately nowadays synonymous with a good brand name, can help you a lot. For example, you would be exposed to an alumni network, you would have a brand name that would take you places, and you would not repent later for not having taken a loan, which you eventually would have paid anyways. Most importantly, let's take a hypothetical situation. In this situation, I as an employer have two CVs in front of me. One says Insead and one says Nottingham. You might be the best fit. But, just because there is a notion in the market that Insead is the 5th best in the world, I might pick up the other CV. Unfortunately, many believe in this notion, which as a matter of fact is justified till a great extent because of the diversity that an Insead candidates bring along. This is not something that is absent from your profile. So, if you want to skip a situation later on in career where, on a global platform, you would be compared with the best of the best schools, you might want to reconsider the option of giving up on top b schools, esp. when you can make it and deserve more than many entering into these colleges.
Loans
Personally, I an't afford to buy a ticket to my dream school. But should something, that is an object that comes and goes with time, be a factor from stopping my dreams? Not at all. There are many many scholarship options available. if you have done a thorough research and have been blacklisted by the entire universe from getting a scholarship, then don't apply. Otherwise, if there is a 0..0000001 % chance of applying to it, give it your best shot. never back down!
The GMAT journey
Tell me about it. I have taken more than 2 retakes. I am not going to stop. Am i optimistic? No. But because I know that i haven't given my 100 percent. I tried preparing for the exam by myself. It didn't work. Some of us need a continuous nudge to go forward. Have you un-turned that stone by joining one of the many available courses? Answer this honestly, have you studied for 2 hours everyday for 20 days. If not, you might want to reconsider the option of giving up on top b schools, esp. when you can make it and deserve more than many entering into these colleges? Still facing issues, I am ready to help you out with a plan. there are a few other and we could all start a group. but don't give up. I used to get a score of 510. I am now at 690. It ain't that great but not less either,given my history with GMAT.
Coming to your main question, ROI. Remember, that money isn't the only investment that you would be making in this case. There is something more important - time. A B School education includes the exposure, the cohort, the education and an experience.
You will not repent your decision to do an MBA from a top 30 b School in the world.