TennesseeVol

My wife and I have a 12 hour layover at ICN Incheon Airport the first week of April and would like to get out and see Seoul. I realize the airport offers free transit tours, however, they are only 3-5 hours long, and I would like to better utilize the 12 hours (factoring in the time it takes to exit the airport/commute to/from Seoul, return to the airport a couple of hours before the return flight home). I am comfortable taking the train into the city and planning our own tour, but my wife prefers a tour guide (and as usual, she wins). Don't really have much in mind in terms of itinerary except seeing the Gyeongbokgung Palace, and hopefully walking through a neighborhood or two (Hanok, Insadong, Hongdae, etc.).

I would like to find a private tour guide that will pick us up and return us to the airport according to the times we will be there (7:00 am-7:00 pm on a Sunday). I've looked online quite a bit and seem to only find a small number of options. Viator, OneDayKorea, TourByLocal are the few I've seen. Most of the tours seem to be around $200/person, but I would like to find something more around $100/person. Do you guys have any suggestions on ways to find a local tour guide?