itch.io

Buy a drink from the coffe machine, for example a cup of milk. Then you go to your apartment, click on your computer and then click "Shop" After that you can put your cup of milk up for sale and change the price to anything above 1 coin (what you bought it for) and you'll make your money back easily. If you repeat this a couple of times with various different drinks and set appropriate prices you'll never run out of money. I have 600 coins currently