Prices generally are getting ridiculous in my opinion. There are still currently plenty out there with reasonable rates, but more and more are pushing themselves above what I'm prepared to pay.
And it's not so much a question of whether it's worth it or not, more a question of why prices have gone up around 50% in the two ish years I've been punting. OK, so some guys are still happy to pay the inflated prices, but they aren't getting anything they weren't getting at the lower prices before and it's not like the girl's costs have gone up that much in the same period.
Stick with girls in your price range, and if any put their prices above your budget stop seeing them and tell them why. Some will keep you on their old rates, but hopefully eventually they'll drop their prices back down to more acceptable rates, and only do future increases in line with inflation - i.e. the same sort of pay rises their customers get.