When truly desperate enough, I always use the violin-Get To Work get rich quick scheme.
It starts with buying, so you need to liquefy some assets, until you can purchase both an empty lot and the 15k violin.
Then you take whichever sim you have that has the best charisma and sell that one violin at 100% markup in your empty retail lot. That should net you 30k, enough to purchase two violins.
I always stop at two, but you just keep selling and restocking, netting that extra 15k with each go. Eventually you sell the last two violins, and sell the empty lot, rich af.