Dear oskar,
For 500 usd you can pick 10 girls in shanghai. When you get here, just buy a "shanghai daily" newspaper and call one of the numbers from the massage section. Negotiate for RMB 500 (not USD, RMB!!!!) max. and they will send you a girl.
You can also go to tongren lu and go to Manhatten bar or Judys and pick one. If you have problem, PM me, i help you! ;-)
Enjoy Shanghai
Iloveshanghai