So, I was writing a review, and I mentioned that a certain provider had delivered a so-so session.  Although she was willing to run the gamut of positions, etc., the chem/connection/fantasy aspect of the provider was lacking.  My experience was consistent with other hobbyists, per the reviews.  I finished by saying something like, “I would see her again if she lowered her price to $200, from the fee she did charge….”

Who are you to say, what is a woman's worth? Personally, I feel your suggestion is rude. Let's not use an alias. lol Sexist.

Years ago there was a poster (Mathesar) who did ratings of providers based on cost, looks, and performance. It was an elaborate analysis that assigned a weight to each factor and seemed mathematically sound.  He eventually stopped doing it, but if you do a search you'll probably find some of his postings.  Ahhh, for the old days.

And so we return the unsolvable problem:  How do you objectively rate a subjective experience?  

Exactly Herb. That's why I focus on the narratives to evaluate whether I think I would enjoy a provider or not. The numbers are kind of a gateway to entry For me. For example, a provider who consistently gets rated 5 or 6 for looks, service or atmosphere probably isn't my type, so I don't bother reading. With providers who consistently score 7 and above in these categories, then I start reading the narrative reviews, looking at her current ads, and searching her prior ads for consistency of pictures, services, prices, etc. And lastly, I look to see if any of the reviewers I'm familiar with and trust have seen her, and focus carefully on their ratings and narrative analysis. It's that analysis that leads me to determine whether I think that a potential date will be a good fit for me.
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As to the OP's concept of using dollars rather than rating points, this is probably a messy, and slippery, slope. Rather than doing that I prefer when reviewers state clearly in their reviews whether they recommend the lady, and would see her again. If the answer is yes that indicates to me that the hobbyist felt her looks, service and atmosphere were worthy of the requested donation (or more if the hobbyist indicates that he left a tip).

It doesn't exist outside of math and hard sciences. Once you get past 2+2 = 4, the speed of light, etc., you quickly get to opinion. Which depends on tastes. And we ain't never gonna all have the same taste.
I try to accept the ratings for what they are--an attempt to bring order to an inherently messy business.  And I look at the consistency more than any one number.  
Infinitely more important to me is what the narrative says--did the lady look like her pictures (again subjective but at least there's a baseline), and what did she do in the sack. For example, as an ardent fan of duos, I'm always keen to see whether a duo session included actual DATY between the ladies. The score alone won't tell me that.

I have seen $600 providers that I thought charged too little, and $200 gals who were charging too much….FOR ME.  Like poker, the dollars even out the game — we don’t all know what a “7” rating means to others, but the dollar is the same for us all, no matter how wealthy or poor you are, it all buys the same item for the same price.  Jeff Bezos can buy a more expensive car, but he can’t buy a different Ford Explorer than the rest of us.  

I remember his amazing math analyses of the providers and his ratings based on some totally incomprehensible algorithm he established.  Those were the days, my friend, we thought they’d never end…..

Most times I never quite figured them out but they looked impressive…. And yes, those were the days.

One day we'll read that he was some autodidact with a 180 IQ who got bored with his grad studies and came here to relax.😆

to the best available computers.  The company was at the forefront in the development of computing and data science.
He was a friend of Doctor Gonzo and I used to see him on Doc's "burger runs."  Sorry to say, he passed away a few years ago.

Interesting to remember some of the names on the list:

Hope he had a full and happy life.

I too am saddened to hear that he passed……