1. Hotels
Hotels are quite more expensive than Hostels and Guesthouses. Most hotels' fare cost more than 50,000 KRW (400 000 IDR). There are 5 types of hotels, the first one is 5-star hotels, 4-star hotels, 3-star hotels, 2-star hotels, and 1-star hotels. If you want to stay in hotel with high quality of services, you could refer to 5-star hotels, which are more expensive than the other types of hotel. There are some areas in Seoul that have 5-star Hotels, one of them is Gangnam. Hotels rate in Gangnam are quite high because of the high price of the land2. Hostels & Guesthouse
Hostels and Guesthouse is the best choices for your accomodation in Korea (Seoul Area). Hostels and Guesthouse cost way more cheaper than Hotels, usually cost around 12,000 KRW (96 000 IDR) until 45,000 KRW (360 000 IDR). There are two forms of hostels and guesthouse, which are dormitory form and private room form. Dormitory form is much cheaper than private room form, but you must share room with another tourists. If you're not too comfortable with sharing room with another people, you can choose private room hostels that cost higher than dormitory hostels.3. Youth Hostels
Youth hostels are hostels that are more cheaper than ordinary hostels & guesthouse. There are about 52 hostels around Korea. Teenager tourists' fare for youth hostels cost about 8,000 KRW (64 000 IDR). Don't worry if you're an adult, adult (more than 25 years old) just cost a little bit higher than teenagers.
YOUTH HOSTEL IS THE MOST RECOMMENDED ACCOMMODATION ACCORDING TO MY COMPARISON AND RESEARCH.