It depends on what type of contest, etc.
Let's take a regular IFBB or NPC contest. You have travel (flight if needed, hotel - two nights, taxi or car transportation). You have misc expenses (food). You have a photographers cost, a writer (if needed), video, etc. It all depends on what you are doing. Taking the pics, downloading, resizing, uploading, making sure all is good - all can take time.
So the costs can vary greatly.