I have not been to yogyakarta for about a year and a half but I can share my experience there are many houses in the residential areas behind jalan malioboro near the mall and train station, you will need help to find these. I took the head becek pedicab driver in front of the hotel mutiara and he took me to about 5 of them.
I met a guy named sandy there and he seemed to know about the scene and speaks very good english. I did not use him to find chicks but he gave me a ride to solo and he was cool enough. Yogya is crawling with hot chicks and if you play the game right you can get them to your room and just give them some money in the morning rp, to rp, is plenty.
I have been amazed at how easy chicks that don't seem slutty at all are to hook up with. I have heard of a place called Corona that is a house with a huge selection of chicks.
As for the lesbian stuff I have found it fairly easy to get 2 or 3 chicks in my room and fuck them all but have never been able to find them that were into other chicks. In fact sometimes they are too she to go with you unless the friend comes too. I hope this info is useful to someone good luck. Its at the corner of the pitch black dance floor, you cant miss it.
The mama-san will be there to guide you through to as to how much. These may be pricey for local standards but cheap for foreigners, this is after all the land of the USD 1. This may be difficult if you are white, since the price goes up based on skin color. I have skin like a buffalo and bargaining skills like my grandmother and in my experience bargaining almost always works and in some cases expected. Whatever you save you can always give later as tips. Price for her company is one amount, her time in your bedroom is another.
