Let's say your school has a classroom or two that are not always in use. Have a talk with your director. Explain to him that your city offers nothing for foreigners and that any school that DID open a class would be the first and only one to do so. Explain "cornering the market." While he's thinking this over for the next few days, conduct a survey of every foreigner you can find. If your surveys later show a high interest level, give them to your boss and tell him that you did some research for him so that he'd have an easier time to make a decision.
Tell him not to worry, that if he doesn't open the class, you are sure you can get another school to do it. Mention that you asked him first because you feel a loyalty to the school, but you and many others really want to study and will go somewhere else if you have to. Chances are excellent that he'll do whatever he can to open the classes.
Classes I surveyed foreigners about included: Survival Korean, Basic Korean, Intermediate Korean, Advanced Korean, One-on-One Korean, Everyday Korean Cooking, Traditional Korean Cooking, Vegetarian Korean Cooking, Korean Culture and Traditions, and Buddhism. I am also checking to see how many people are interested in taking group tours conducted in English throughout Korea and things like that.
If your school is struggling, this may be a very good way to make the needed extra money. If your city offers nothing, your school would have the only classes available and would probably not have a hard time filling them up. Also, you can probably talk your way into free classes or at least a discount. You probably live near your school, so you wouldn't even have to worry about a commute!