One of my sims didn't have enough money to pay the bills for his pompous San Myshuno penthouse, so I had him travel to various worlds and neighbourhoods, digging out collectibles, harvesting plants from other sims' gardens, and selling them all until he could make ends meet.
Also, since Seasons, my currently active sim families have won the lottery twice out of six times, I believe. I don't know if it's possible to create a custom lottery, but that might be another thing worth trying: Just create so many lottery holidays and buy so many tickets until you win. Granted, you may waste a few hundreds of simoleons until then, but the payoff will more than make up for that, and if my previous experiences are anything to go buy, the odds of winning the sim lottery are way higher than in real life!
