Pit
Unfortunately your story is somewhat common in Ukraine and applies to other areas of business, not just prostitution. It is right what was said, you can learn Russian, spend years of your life living in Ukraine / Russia but at most you can never claim to understand how russian's mind works. The mentality difference is absolutely vast and it even exists with young people, who never had to wait in those lines for loafs of bread. The issue is that Ukrainians especially have a very hard time grasping such concepts as supply and demand. Again, not speaking about prostitituion only but many spheres of business. They do not understand concepts such as optimizing income based on market conditions at the time.
However, the other thing I would suggest is that it is possible the girl you spoke to simply did not like you. In other words, if a John came up who she liked, she maybe would have quoted a lower price or would be willing to negotiate. This does happen as for many girls this is a part time profession (they are students during the day or whatever) and they suprisingly can be picky with Johns.