Often agents and online agencies do not explain the "fine print" of different promotions like Early Saver but it is up to the buyer to understand what they are buying and the ramifications of canceling.
If you are before final payment and do not have insurance then you may just have to eat the $50.
If you are after final payment and don't have insurance I am sorry. Work with Expedia and see if you can apply the money to another sailing. They may do that minus the $50 change fee.