The Car crushing place pays out 150 per vehicle destroyed in Los Santos every week.Take a bus down to a two lane highway.park it blocking traffic and let it build up.place a few charges every dozen or so feet and when theres a big enough blockage of traffic.do your worst. I cant confirm this but from my understanding of the stock market the liberty city one is tied to in game and you can track the times best to sell and buy stocks. Some side missions that you didnt complete will pay out pretty good lump sums like the bounty hunting missions.
If you get at least three properties that pay out for each character youll be looking at 15-27k per character per week.
Weed Farms.I hit one today and got almost 10k from it.Theres quite a few around that I know of. Armored Truck Random Events continue to happen once a week at Paleto and numerous locations in Los Santos.Theyll get you some change.