Well, I am not huge fan of
"reaching the fifth base", but I dealt with one
girl who was quite skilled in this art:
http://www.vipdosug.spb.ru/7_1.htm
phone: 812 944-21-83
Name: Maria (Marianna).
Mention you found her on Internet.
I paid approx. $100-150
(cannot recall as usually a good tipper anyway)
for 3 hours at my place.