I've done the "look for a new girl in anger" shit when a girl's price goes up. In short, I learnt that it's usually a bad move. Do the numbers. How much more can a girl's price go up? 20%? Let's say it goes up a ginormous 40%. You go take a punt on a new girl and she turns out to be a dud. That's a 100% loss on the new girls rate, vs a probably good punt on the regular (even more likely because she's getting more $$$) paying 40% more. Not to mention the time factor... a dud punt is a waste of your time too.
You might get lucky that the new girl is good, but what are the chances of that happening at exactly when you want it to happen?
