This is not as naive a question as you may initially think. The same issue happens here in the States.  Here the ladies will advertise their hourly rate with a few words about the performance you will receive, accompanied by one or more photos to appeal to your visual senses.  [The photos are often not at all representative, but that is another issue.]

There are many different threads on this site regarding prices: Service price range, Price = Quality, Price wars, Prices of the girls, etc.

So I am asking, in HK or Macau or the mainland, why the tremendous variation in advertised rates.  Stating the question one way:  Why is any lady able to charge as much as she does ?

I have listed a few ideas why below that come to my mind.  It would be of interest to know what the other bros think.

Past experience - - the lady has a positive reputation as a solid provider in the mongering community.  This generally allows her to charge a higher price.  Also if you happen to be a repeat customer with a good previous experience, you are probably more likely to open your wallet a little more.

Youthful age - - it seems there is something of a cut off age, where the WGs loose their appeal to active hobbyists.  Too young needs to be avoided for obvious reasons.  Too old and they loose clients.  Those ladies who tend toward the lower legal ages seem to command the higher prices.  At least, this is my observation.

Height and weight in proportion - - a highly subjective issue in any forum.  Some of us like the very thin ladies.  Others prefer a little more body mass.  So the idea of 'in proportion' really depends on personal preference of the hobbyist.  It does seem that the females that trend toward the lighter weights for their height can realize higher prices.

Positive reviews - - in the States this is definitely a solid indicator the lady can charge more.  I know more than a few hobbyists who first check the detailed reviews before ever considering picking up the phone to call for an appointment.  One or more bad reviews can be understood somewhat.  All bad reviews will definitely cause a lady to loose clients.  Supply and demand rules are in effect: if no demand then the lady cannot very well expect to charge a premium rate.

Special skills - - sometimes a hobbyist is searching for one particular performance aspect which outweighs all the others.  Not all girls will open the back door, or allow BBBJCIM, or some similar.  It seems like a WG known for a particular skill or niche service can ask and receive the higher prices.

Incall versus outcall - - universally, here in the States the WGs will charge more if they have to travel to you or your hotel. [To me this seems more of a transportation service charge, than a premium for personal issues.]

Particular body attributes - - large [or smaller] boobs, long legs, especially pretty face, full lips, tiny waist, very long hair, etc. etc.  This hobbyist is crazy for a full rack coupled with a tiny waist.  Other bros must have similar goals.  We all have particular body items we find attractive.  It is believed that some WGs can capitalize on their unique shape or anatomical gifts and secure more money because of it.

Nationality - - a lady is from some particular national origin.

Other - -  simple supply and demand, local economic conditions, hunger, or  ?  ?

I did not want this to be a survey. I am more interested to know why the bros are willing to part with more money for one provider over the others.

As you said, if you make a search on "Price" in the "mongers' lounge" section, you will find many threads discussing that topic.

I think in HK your question is valid only for Freelancers you pick in the street.

For other girls in the DB, I don't think there is a real comparison to do between one particular provider and another one, it's a more a choice between the roughly 3 categories of prices :
1/ Hotel girls : Young and fresh PRC girls, nice room, convenient, discreet, but illegal (but feels safer than 2/) and more expensive.
2/ PRC walk-ups :  Young and fresh PRC girls, can see the girl before accepting, but simple room, guys walking around and queuing,  and risk of raids
3/ Local Walk-ups : Legal and safe, but girls are older and experienced (can be good or bad)
(You can also add 1.5/ Phone appointment girls)

PRC are said to have better service than locals, and then, depends on your luck and the girl's mood. The other criteria you mention (look, skills, reviews) will just affect the availability of girl.

The price you pay depends on the category you feel like going for... Then, there is a price variation depending on the location. So when you chose any of those category, once you get to the place, before picking any of the girls there, you already know roughly what price you will pay.

So to answer your question, I think in HK DB girls, you chose a price and category first, and then only, you will chose the provider.

I think it is a bit of an odd question.  

Basically comes down to three factors, in order of priority:-
looks
looks, and
looks

If you really want to split hairs, there are "specialist" markets that have their own pricing logic - e.g. kinks, or A-levels, etc. - but within those specialist market the same three factors determine the actual price.  

Service is only measured after delivery, the vast majority of punters are too lazy or in too much of a hurry to read reports, and very few girls actually HAVE any kind of a third-party report to judge her by.  
Few girls INCREASE their prices for regulars ... and equally few ever reduce their price to encourage loyalty, beyond giving the occasional freebie ... ergo, the price is pretty much going to be the first-encounter price, and that is based on looks.

In mainland, price was make by the manager and sometime decided by the enviornment.
Of course, girls with pretty face and thin body and a big boobs means you should pay more for them.
But there is also other principle such as the relationship of specific WG with manager or skills.

However, to me, face always rank the first. And she must carry a big smile we when first meet. Cause, you know, people would be depressed for any reason. Everybody could have an awful day, if she doesn't feel good, how can she serve you well.
That is my rule.

Interesting thread. I think when you are visiting for a WG, you are paying for her time and service. The advertised prices for WGs clearly range from the amount of time you book her for and the services she provides. However, whether the punter selects the WG clearly depends on whether she is his type. Every punter has a different type and fetish with different time and service requirements. This leads to multiple prices for each one of these factors. Then the theory of ECON101 applies, where the market price is set by the laws of supply and demand based on all these factors for each working girl.

Ok, I understand there is grouping based on the above parameters, but who is the one that sets the actual price within the grouping.

I guess more simply stated, does each girl set her own pricing or does she get "help" from some where telling her what to charge?

Che'lu

Whichever group of girls has a better editor to PS their pictures can charge more, it's called marketing! I'm sure Papasan/Mamasan gets the larger cut of the increased fees though.