I would recommend finding a plan in your state has a lower cost. N is a good plan, but you have to remember in the med supp market, each plan F offers the same coverage as any other plan F. So if you could find a plan F; with say United of Omaha - division of Mutual of Omaha (in NC they are the least expensive this year) you would find their plan F is about as much as AARP's plan N. Why not get more coverage (Plan F vs Plan N) for your money.
Remember, your higher than normal premiums are paying for some of that advertising. When was the last time you saw Mutual of Omaha advertising a medicare supplement plan???