The item exploit trick works!
If you want to be an egg farmer, make sure you have an extra XBL profile. I would HIGHLY recommend beating the game on your own at least once; this is a form of cheating and makes it extremely easy to upgrade/buy all the weapons, diminishing the challenge later on.
-First go to level 3-1; go to the island where no enemies appear when you first depart, and you'll find a lone chicken inside a hut.
-Follow it and/or wait for it to lay an egg. If you're lucky, you'll get a golden egg, which is worth $1,000.
-Make sure you have SAVED your progress before quitting! You need that egg in your inventory.
-Now select any stage to start on. Un-equip everything except the egg.
-When you have control of the game, press start on controller 2. Load your other profile and create a save.
-Now have Player 1 (you) give the egg to Player 2.
-Quit the game, but make sure that the Player 2 profile SAVES. It doesn't matter with Player 1's.
-Now reload your game or select any chapter. Keep your inventory slots empty.
-Hit start on controller 2 and load up the profile you just saved.
-Give the egg to Player 1.
-Now quit again, but this time, save Player 1's profile and NOT Player 2's.
-You can repeat this trick as many times as you want to, and do the opposite to build up Player 2's inventory.
-I kept doing this until all nine of Player 2's inventory slots were filled up, and now when I do the trick, there's 45 eggs to take.
-That's $45,000, and the whole thing only takes 2-3 minutes to do each time! You can buy/upgrade everything in no time. No more grinding for cash!