A couple of things. First off, the lack of support for 170 and 190 is kinda funny as 150 seems normal, yet the others 120/140/160/180 is based on only getting 20s out of an ATM, while anything over 200 means some prior planning as most ATMs cap at that amount.
Second, sliding scale, when I was stationed in Hawaii (Oahu), there was a sliding scale. There was the Military discount, Local rate, Tourist rate, and Japanese rate. I was talking to one of the women I saw and she explained that the working girls knew that military pay sucks, especially for junior enlisted, then the locals, who could afford to live in Hawaii, made a little bit more. The Tourist were visiting and saved up money to monger in the islands, and the Japanese were more than willing to drop top dollar, especially for a white woman.
Finally, a provider has to take into account expenses, how many guys she wants to see in a day, and how she wants to act with clients, how the economy is, what is the cost of living in the area she works, and finally what kind of reputation she wants to have. We review the ladies here and I'm sure business goes up and down (no pun intended) based on reviews. There are women I considered, but after checking reviews, I have passed on, while there are some I wouldn't have considered (due to lack of pic &/or price) that due to good reviews I have seen. A lady is going to charge whatever she sees fit to do; us guys are going to decide whether or not to see them. If you are a regular, she may or may not charge a different fee, but again, it’s up to her. Just my two cents (again).