For self-service, go to Jinhans. The environment is not bad. It is located on the fourth floor of Ladies Street. Downstairs is Watson Cinema. You can eat and watch movies at the self-service. It is quite good. It seems to be 36 yuan per person.
Western restaurant recommendation: Roman, a time-honored Western restaurant in Dandong. The environment is very good and the key is convenient transportation. After eating, you can take a walk to the riverside. It is very good. The price for two people should not exceed 100 if they don't go there for the food.
For Chinese food, we recommend Sun Moon Lake. It is a time-honored hot pot restaurant in Dandong. The environment is good and it is close to the river. The price of 100 yuan should be OK.
Korean food recommendation: Goryeo Hyang Bar. It is located on the riverside. It seems to be run by Koreans. The facilities, environment, and waiters are all Korean-style. The price is 100~200 and you can eat well.
Japanese recommendation: Hokkaido. It's on the riverside. It's quite authentic. You can eat some sushi for 100 yuan.
For the above-mentioned riverside places, you can go for a walk by the riverside after dinner, which is great. In short, these are my favorites and I hope they can help.