I do not believe that there is necessarily a correlation between SP services and price unless a woman has built up her business.
As guys have said there are many high-priced SPs whose service sucks. There are also many lower-priced SPs whose service sucks.
There are many high-priced SPs whose service may be good just as there are low-priced SPs services who may be good.
However, I'd suggest that most higher priced women are, on average, much more physically attractive than the lower priced ladies. However, that doesn't mean that there aren't exceptionally hot ladies at the lower price bracket nor does it mean there aren't unattractive/less attractive women at the higher price bracket. But I'd suggest that most women tend to price themselves based on how they percieve they physically look relative to the competing market they are in. THAT IS THE BIGGEST CORRELATION WITH SP PRICING...and unfortunately it is a woman's looks which is also what hooks many of us guys into seeing an SP for a first time without maybe considering other qualities of what makes a good session.
Those of us experienced in this hobby learn the hard way, of course, that just because a lady is hot doesn't mean she will necessarily give you your money's worth.
I'd also suggest, through experience, that there is a correlation between how high an SP likes to price themselves and the workload that a lady wants to take on...using the rules of supply and demand economics (AS A GENERAL RULE...OF COURSE THERE ARE EXCEPTIONS). I'd argue that most ladies who price themselves at $300 + an hour are, by nature, ladies who do not necessarily want to take on the same number of clients per day/week/month than the ladies who are willing to price themselves lower (ie. don't necessarily want to work as hard). That doesn't mean that there aren't women who charge high who aren't willing to work, but I'd suggest that there is a correlation...
...and in this vein I also believe, in my experience, that this oftentimes is also a reflection on the mindset and work ethic of many of these women...and that many women who are apt to be willing to work more dates are also more willing to give more effort in the session whether it be because they recognize the value of getting repeat business by doing this, or maybe even pride in what they do. As far as the high priced ladies...many of them are just fucking lazy and don't give shit service. This seems to happen way to often.
Now of course there will be the cream of the crop - the hottest of the hottest who give unbelievable service and market themselves to a clientelle that can afford to pay sky-high fees, and these ladies will work their asses off. I'm not talking about them.
But I believe in general that a great deal of the women that price themselves in the stratosphere aren't necessarily willing to work hard on the service end of it. I think for the most part they rely on their looks, get the guy in the door, take the $$$$$ dough, and then are happy to get the session done with asap and go spend their cash.
On the other end, I have found many hot women who price themselves reasonably in order to build a clientelle who will repeat often...these women are building their business. They may even eventually increase their prices once business reaches a certain level, but during the early stages of their career they are willing to work hard to create this demand. This is the type of woman I seek out. Unfortunately there may come a time where those women price themselves out of my range - but these women are out there and they are great when you find them at this stage.