I think the game is shortchanged by 10 dollars. I spent hours looking around but I couldn't find anything. It seems if you want to get all the girls you will have to give up the warehouse.
If that last $10 is there then it's so well hidden that even going to the point of checking random plots of sand on the beach couldn't find it.
Please consider adding that final 10 if it isn't already there, or lower the price of the hooker from 30 to 20. As a completionist it bothers me greatly not being able to get everything done on a save file.