This is my perspective.
I've donated as much as 7/hr and 12/hr for doubles. That said, majority of the trans women I see are in the 2.5-4 range. For a cis woman, the most I've donated is about 7-8/hr.
One thing I can say for sure, is that nothing makes me close a tab faster than a provider who lists a high price, and then a higher price for "VIP" without even hinting what that VIP service will be and those providers typically have little to no reviews.
Another factor for me, is the competition. Us customers are not exactly the problem here. It's just the free market. You have Thai providers who are pretty much willing to go FS AND provide a very enthusiastic performance for 2-3/hr and that even includes a decent massage on top of that. In my market, you have Latinas quoting 3-4/hr that will really go to town on you.
But, I've also gone 7/hr for a very reputable Latina provider here and practically went 6 each for doubles on a pair of reputable Asians. Keyword REPUTABLE. If a new laptop brand came out that you've never ever heard of, would you pay the same price for that laptop vs a Macbook that is known to be tried and true?
I'll admit though, one of the biggest reason I was willing to pay this much was because of size. Pun intended. So, even if it's fucked up to say, genetics play a role in how much you can charge. This goes for both cis and trans women. People who participate in this hobby will have certain preferences/kinks. If you are one of the very few in your market who can satisfy specific kinks/preferences, you can charge more.
Ultimately, what you can charge depends on your market. Do you provide a unique enough experience or look to justify your costs? Cause if you don't there are a lot of options out there.
I apply all of this to both cis and trans women that I see. If your looks match another provider that costs less and provide a similar experience, I'm going with the lower cost and there is absolutely nothing wrong with that. You'd do the exact same thing with whatever you are buying wouldn't you?