Since there seem to be several people who don't quite understand how the money system works, here's a little tutorial.
First talk to the redhead at the cafe and select "Do you have any job openings?"
Now you can work at the cafe every morning for $50 a day.
Once you have got the smartphone from Nicole and reached a fair amount of money, select the laptop in MC room then Shopping > Favours from Bogdanoff > Dump it (Decreases BBC value by 20%)
Open the app on the phone and deposit the money but keep at least $ 50, then click on "buy" close the phone and wait for the next day.
Go to work and back to the bedroom (now you should have at least $100), select the laptop > Shopping > Favours from Bogdanoff > Pump it (Increases BBC value by 100)
Open the app on the phone, click on "sell" and then "withdraw". Done!
I know that there's also an option to reset BBC value to 10 but I didn't need to use it.