Help with itinerary and $ goal for Seoul, Korea

Hello, I am trying to save up to travel for a week in Seoul Korea next summer, but have no where to start. I have never traveled before and I live in the us and have only been to the three surrounding states around me. Could any of you give an imaginary number as a goal for myself to save to? I will be with my partner and friend with her partner, but want a number for each of us. We want to stay in a hotel that’s not luxurious but not a hostel. We want to experience nice restaurants as well as simple and even food stands. That is where most on the money will go to is the food, but also to any Knick knacks. Our age group is 21-23, if that helps. Please let me know if more info is needed.