I found another easy money hustle that Rockstar will probably fix in time...
The first 5 or 6 story missions on XBL will pay out big $. Over $100 each, but only the first time you do them. After that theyre worth only a few dollars.
After doing the first 5 story missions ( possibly 6, not sure ) you can start over and re-create a new character while still keeping the $500 or so that you earned from the missions. Yes, your character will start from level 1 again, but you can bank thousands with this method if you have the time.