There are a couple of items I think are more important than the others. These are the ones that will make you more look like Joseph, and you thus can not replace them. For both the tank top and the scarf there are no substitutions.  You can not just use a shirt or a sweater in dark green. You need to be wearing a tank top. The scarf too is not replaceable by something else. You will need to find one that is green with yellow stripes. The combination of these two items is going to make it a lot easier to recognize your cosplay.