The $4 bus ride to Gyeongju is worth it for the hike up Nam San. You catch the bus from the Ulsan Bus terminal. Once in Gyeongju take city bus 10 or 11 or take a $6 taxi to Nam San. The hike is about 45 minutes up ( mostly up hill). Along the way there are several ancient Buddha statues and reliefs. On the way down my group got lost and ended up bush wacking and repelling for two hours (There are many paths to explore and get lost on). Either bus back or stay in a love motel; we were told that there are no Jimjimbongs in Gyeongju.