The violin idea posted above is a good idea. I did that some time back with my SuperSim to get her in a expensive house. She was in the house in two days.
Takes a bit more time, but gardening is a good money maker. Maybe this would be a good way to bring in money now, and you could carry the plants over to your new home to help pay those bills. Plus, it's a money maker that can be passed down to the next generations. UFO fruit, DragonFruit, and blackberries are all good money makers (from my experience, in that order of value).
Paintings and Writing are a little more time consuming, but can bring in some good money. I do writing when I want to have a steady flow of cash coming in even when I don't feel like having my sim work all the time (she can take a day or two off for fun, but she'll still bring in her royalty payments, unlike painting, which if she doesn't paint, no money flow). Though, I think (haven't tested, so this is just my opinion right now), that painting can be more of a money maker if you plan on just pushing out the paintings. I have had abstract paintings that go for over 10 grand.