its not worth cutting out the holes for weight reduction, particularly as the one in the video has them removed in exactly the wrong place. thats why chetes have a bulbous head on them to add weight where its supposed to be. Stainless would be way more trouble than its worth, you should get used to the idea that you need to dry it after use, oil it when possible and be ready for oxidation that is sure to come.
What are you going to be doing in the amazon? If your flying over and this is just for emergencies then you need one thing if your hiking the length of it then you need something else. 350$ is a good price for a custom functional chopper.