Cheats, Codes & FAQs
When you pass a checkpoint in solo mode in the campaign, drop an item you want to duplicate. Commit suicide with bombs or molotovs, and when the respawn timer starts press pause. Then, reload your game from the last checkpoint. When you do, you'll still have all the weapons and items you dropped, but those items will also still be on the ground where you dropped them.
Get a hammer and baseball bat from the warehouse, then use fast travel to go to the church and sell the hammer and bat. You'll get around $400 for these items. You can then go back to the warehouse and find those same items again, then take them back to the church and sell them for another $400. You can keep doing this as much as you want to get lots of money.