I priced the particular souvenirs I wanted in Itaewon and bought them in Insadong. There were a lot more souvenir shops in Insadong compared to Itaewon, which had more American goods and clothing shops. Generally speaking, any time you buy an American product overseas, you're going to overpay for it. So, I went to Insadong knowing how much the 'going' rate was for souvenirs. Fortunately, the rates were similar in Insadong! I did end up overpaying for a t-shirt but only by 2,000 won, which is almost US $2. No big deal in my mind. You're supposed to bargain in these places but I didn't bother. Instead, I shopped around to see what the prices were like in different shops.
Dongdaemun Market, to my surprise, is across the street from Gwangjang Market. O_O I was in that area my first day in Seoul! :o\
I met up with my sister and her roommate for dinner. We had a dish similar to the Korean BBQ from earlier in the trip. We followed that up with dessert from Caffe Bene - YUM. [Note: We went to the Sinchon location, not the location described in the link.]