Unlimited money PS3: Go to Dorians's house in the Impearial city by the stables, and bribe him until he is full. He will have more money that way. Make sure you have somthing to paralize him then click "x" on him and then you can take as much money as you want.
On 360: Bribe him and then kill him and you can take money from his corps.
On 360: Bribe him and then kill him and you can take money from his corps.