Prices used to be about £25 but I'd expect it's up a bit by now.
On foot:
In the Centre of the City is Plaza San Pedro between the Pino Suarez station and Merced. Lots of girls on the North side of the road. When you get to the end of that road, there at Merced, go north staying on the West side of the road for another 100 yards and there are plenty more girls there too.
Car preferred but can do it on foot:
Viaducto station to Xola station. Calz de Tlalpan. Girls are on the West side of the road. The area does go down to Nativitas station but the best lookers tend to be at the Northern end.
Car needed:
Calle James Sullivan between Calle Rio Amoy and Calle Jose Rosas Moreno. Girls are on the South side of the road. Night time only.
Buenavista station area to the east of the Walmart up to the Zaragoza, and Calle Orozco Y Berra, street limits.