You can use the filters on the "Find an Escort" section of the Review Section to enter a rate, along with other attributes and limit the number of profiles that come up to those providers you can afford.

In NYC you can have a great time between $300 and $600 an hour. Less than $300hr is scrapping the bottom of the bucket IMHO. I don't fuck with the +600hr girls out of principle. Just don't think their pussy is worth that much.

and I am going to be "nice" lol

 
NO, there is no need to pay $500 unless you can afford it. Now I will concede that at rates below $200-300 hour, depending on market, the "quality" of the experience may suffer, but to answer your actual question, $500 hr is not a "minimum baseline" for quality companionship, although as you said, some women are certainly worth every penny they charge.

 
My advice is to hang out on the newbie board for a while, ask whatever questions you might have and be sure to spring for the VIP membership which will allow you to peruse the reviews to make sure the "bargain" you think you are getting at that low price will really deliver the goods or just take your money and leave you unsatisfied.

rates very a great deal by location.  I think in some cities the rate of $500 for an hour is fairly normal.  In others it might be $300.  I am sure there are a wide range of rates, women, and options in most areas.  As mentioned do your research and enjoy.

OP (Original Poster) also posted to the ISO board and says he is in Ohio ... not a place that I know.  
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You might look for Massage Parlors or FBSM (Full Body Sensual Massage) which is both more economical and less pressure. It seems that you are new and nervous, among other things. If you go for a massage and you, um, aren't up to it because of stress or nervousness, you are only out a smaller amount and will at least get a comfortable and comforting massage. (Another possible newbie experience is to finish much faster than you hoped ... one or two minutes! Don't worry about that, either. ... Although from your ISO post, that probably won't be a problem?)  
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HOWEVER! Read the Newbie board and also read the reviews about any MP or FBSM that you might seek out. Don't just walk into a local place that says "Massage" on the sign because it might be a place that will kick you out if you ask for "extras".  It would be best to find a well reviewed FBSM whose reviews show that she knows how to take care of a variety of clients. I will guess that you can get a massage with a happy ending (HE) in your area for $$ or less.  
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Good luck!