The Pleasure Principle is the only spot worth going to in Cancun, and it is truly world class. Ask any local about it, or better yet, any Mexican from Mexico City (the ones with money to blow), and they'll tell you it's legit.
It's the same place as
cancunescort.com that others mentioned above, but I'm pretty sure their main website is
www.pleasure-principle-cancun.com these days. It's a full service escort agency not a true massage parlor, so keep that in mind when setting your expectations. You can definitely start off with a massage before you get down to business though
As far as prices go, it is more expensive than your other options. But "expensive" relative to what? A busted to slightly-above-average independent off the street? I'll pass...
In my experience, there aren't really any comparables to this place if you are in Cancun. First, this is easily one of the best agencies in the country. And if you're from the US and haven't traveled extensively, you haven't experienced anything like this place. Second, you're not paying for a massage or lap dances, and then trying to negotiate some extras in the back. You are paying upfront for an hour of TGE. You are paying for quality that is better than anything you will find off the street or in the strip club 99/100 times.
Now, if you are just looking to spend as little as possible on a street walker, then by all means knock yourself out. This place is likely out of your budget, or you are a hardcore monger. There is no shame in either, this place probably just isn't for you. I'd suggest going downtown and away from the hotel zone, but be careful folks -- it's actually real life Mexico over there.
Stay far away from the strip clubs, especially if you are on a budget. Just don't do it. You will get ripped off a hundred different ways before you even start negotiating prices with a stripper. When you add up all the $$$ you spent on cab fare out of the hotel zone, cover, $20 a piece drinks for you and your stripper friends, plus the $150-$200+ you negotiate for her time, and possibly the $100-$150 you pay the house in exit fees to take her back to your hotel, you'll end up spending at least as much as you would at the Pleasure Principle. And you will pay because no one wants to go through all that trouble for nothing. However, you will not feel like you got your money's worth the next morning.
I understand that a lot of people are looking to find a hottie on the cheap in Mexico. That's completely valid as long as you realize you are searching for diamonds in the rough. This is Mexico, not Colombia. How many $100-150/hr duds are you willing to blow through before you find your diamond? With that in mind, is $300 really all that much to avoid the strip club racket and to essentially guarantee yourself an hour with an 8 or 9?
Personally, I find comfort knowing that my money is going to be well spent. Overall, I think it's totally worth the price, and is the pro move when you are in Cancun.