Guess I belong to the minority. When I buy sweets in JP for my family, I always go to Lawson or Family Mart, where I fill my basket with 20 different things. Usually cost me around 3000-4000 yen, which is a lot cheaper than what you can get at the airport.
The only downside is that you don't get the beautiful paper wrapping that the souvenir sweets have.
IF I wanna get fancy, I will shop at the souvenir shop in Skytree.