First of all, do not expect straight up prostitution if that is what you are asking. They deliver coffee from the tabangs and they will service a foreigner, but their primary purpose is companionship and conversation. The coffee is about 6000 won during the day and about 10,000 won at night. If she likes you she may stay longer. If you are a foreigner and speak Korean, she may stay longer than that. However, while she is there, you can negotiate anything. Prostitution in Korea is officially illegal, but delivering coffee to someone's home is not. BTW, there is usually someone waiting outside close by or timing them and will come looking for them if gone too long. This is for their safety (especially with foreigners) and to keep them from carrying too much cash. What may better serve you is sports massage.....another colloquial for delivery sex. That cost more than the coffee girl , but there is no confusion. Many come with a menu. FYI, all fully licensed actual massage therapists in Korea by law have to be blind. A sighted massage "therapist" is more than likely a sex worker.