First off, thanks I.D. for this great topic. Yes Bilkpo, it has been done to death...but it's worth discussing.
One thing I believe is that estimates of 3% inflation for Costa Rica are ridiculously low. I would guess that Irish Drifter's figures are closer to correct.
Secondly, I think that the neat, symetrical $100.00 is a psychological decision point for both monger and courtesan. It steps her into three figures, two zeros, real dollars. This is why OTOH it's a difficult price point for many mongers to accept. And I don't blame those of us who steadfastly refuse to pay cien, particularly those of us who are educated about the local economy, what skilled workers in other trades are paid, and who accept the fact that comparing the U.S. economy to that of Costa Rica is falacious.
But the magic cien is a sticking point for many on both sides of the bargaining table. I agree with Zippy that many girls will deliver extra time/service as long as their cien price point is met. Such was the case with my one and only BM takeout.
Margia, a 28 year-old Colombiana with perfect bolt-ons and the sweetest attitude of any working girl I've ever known wouldn't budge off $100.00. Period. In our negotiations, she also refused DFK, DATY and BBBJ.
What happened?
As she came highly recommended, I went for her anyway. 3 hours later, after much DATY, DFK and a rocket-ride of a BBBJTCOF&T (on face & tetas), I was glad that I paid her the cien. And guess what? I paid her up front. I know, I know...
Her hourly rate for a date with me came to less than $30.00, plus a very modest snack at Restaurante Del Mar and 650 CRC cab fare back to the BM.
I would advise any newbies reading this to consider the following when negotiating in the KL, BM, NYB or MB...
First, don't automatically refuse to pay cien. Just make sure more time is offered, and the services/fantasy you really want.
2. Remember that many girls in the bars have either no place to stay or at best a crappy roach motel in which to spend the night. Your jacuzzi suite at the Presidente, even your clean, cozy, no-frills room at the Castillo will seem like the Ritz to her; TLN should be no problem at no additional cost, if you catch the right kitten at the right time of the night. "Quisiera desayunar desnudo contigo" (I (would) want to have breakfast naked with you) is a phrase to use with Miss Right for all night. Remember that the ones who have no family commitments may still dread the long bus/cab ride home and will want to stay with you simply for convenience, or only a few extra bucks.
3. It is not your job to overpay her, to give her a "better life" or to feel sorry for her. If she demands the higher prices, say $70.00 and up, let her know that you expect extraordinary service and fun for that money.
4. NEVER compare U.S. prices to Costa Rican prices in the presence of the girl.
If OTOH she pulls the old "Putas in the U.S. make $300.00 per hour" crap, remind her that it costs four times as much to live in the U.S., and that the $300.00 is only enjoyed by college-educated supermodels who speak three languages fluently.
5. Negotiate everything in advance. If you don't negotiate something you want to have happen and it doesn't happen, blame yourself. Some of these girls will want to do you only partially undressed, some will try to flee after less than the agreed-upon time, some will want to stay all night when you want them to leave... so negotiate before taking the long walk to your room.
The Anglo phenomenon of "priced as marked" is somewhat still foreign to the latin American people, who all expect to haggle a little bit, particularly when it comes to services. Don't be afraid to state what you want, and make her state her price before you negotiate for more time/less money.
Hope this helps.