Networth contributions are not based on the current market value, they are kind of a flattened average from a recent time period to reduce the impact of market manipulations - similar to how a brand new item is ignored from NW total until it has been in the game a while and the price settles.
Right now cans are in a dip due to Christmas circulation increase, so their networth value is higher than their market value.
Edit: Note, due to the elimination happening so soon after halloween, the prices for energy items stayed higher than normal. It wouldn't be quite so noticeable otherwise, as they would have already been falling from the halloween circulation increase prior to the Christmas surge.
You will always see some disparity though, this is on purpose.