You can get free treasures worth 11,000 gold and a RPG at the start of Chapter 3-1, "Marshlands"--all without need for any use of ammunition or trouble killing zombies. Start Chapter 3-1 "Marshlands" and skip the cinematic if you do not want to waste time. Straight at the first dock, go to the vases to find a Ruby (Pear) on the mask (1,000 gold). Go straight to the center of the lake to find a Silver Chalice/Idol in the box of the hut (2,000 gold). Go northwest. There should be a half-sunken boat on your way there, with a RPG in the silver box on the deck. Go to the platform at the northwest. Along your way in, there should be a Beetle (Brown) on the fishing fence. At the platform, notice the Silver Chalice/Idol in the box of the hut. Jump down into the pool. There should be another Beetle (Brown) at left ladder up. (all totaling 4,000 gold). Go up north of map and to the end of the village. Help your partner up the left tower to collect the Silver Chalice/Idol in the box (2,000 gold). Note: Do not take the key piece in the box on the left tower; it will trigger enemies to appear. Finally, go to the southwest village with a long stream leading in, then go straight to the center platform to open the box. You should get another Silver Chalice/Idol (2,000 gold). Note: Do not head elsewhere. Go directly to the box at the center platform. If you go towards to the other huts, it will trigger the zombies to appear. Save and quit the game, then sell the treasures worth 11,000 gold in your inventory. Sell the RPG for another 1,000 gold if you don't want it. Note: Make sure not to pick up any of the puzzle (key) pieces as this will trigger the enemies to appear. You can break as many vases and pots as desired and collect ammoand gold bags, but do not pick up the key items. Do not bother to go to the east village to get the other Ruby (Pear) as you might be killed by the Crocs. If everything is done correctly, you will not encounter any enemies but get 11,000 gold worth of treasures and a free RPG.
In addition to the above, there are other hidden treasures throughout the area. On the first area with the vases, there is a Brown Beetle on the tree to the left of the key piece. At the area in the center of the lake, you can find another Brown Beetle on a post just left of the dock. Also, collect the eggs from the back right corner since they sell for 250 gold each. Also, wait to see if any of the chickens lay eggs. Sometimes they will lay a golden egg worth 1,000 gold. At the sunken ship to the northwest, there is also a beetle where the ship meets the water. In the area to the very north of the map you can find a ruby on a cow skull on a post near the first hut on the right. In the area following the long stream to the southwest of the map, there is ammo skewered amongst the posts surrounding it. In addition, there is another beetle on the tree to the right on the way around to the back. If you have trouble finding the beetles, look for purple flowers growing on posts and trees. Also in the north area, there is an Emerald atop the cow skull perched above the sacrificial altar--shoot it down. With these additional treasures, it brings the total to between 20,000 to 23,000 gold per run and you will still not encounter any enemies as long as you don't pick up puzzle pieces.