In the penthouses you can have planters. I would get a money tree if you can (5000 points) &/or several dragonfruit plants. You can start by just getting at least one dragonfruit. I have the plants &/or the fruit in the gallery. (Same username as here.) Downloading the room they're in costs about $300 or so, but only about $20 or less is the plant - there is no fruit on the plant, so it's cheap. Once you delete the room and table you'll get the other money back. Squeeze out the money to get the plants started and tend them... before long they will be your income supplement that will make the bills in the penthouse affordable. You can even expand the garden by re-planting some of the fruits and have one sim with no job but painting, selling paintings (as @Simsandra mentioned, once the painting skills are high selling them makes a nice income), gardening and selling the harvests. Works really well.