Thanks for all the reviews of the £100 bargain girls you've seen
Wg pricing varies by area and type of girl. A lot of EE girls are cheaper than English (& other nationalities) so you can be looking at £100-120 for EE or £140-150 for English. We punters swim in whichever pond we have the readies and inclination to.
A girl can charge whatever she likes and if she has enough punters to suit her needs then fair play to her. Bigger cities with plenty of choice tends to drive the price down.
A popular girl could get away with a price rise but will lose some punters by doing it, dusty phones makes them drop their prices.
I didn't read all of the saafe article but it seemed to be relatively sensible