Well, cruise lines do tend to drop fares for non-revs at the last moment. The best rates are booked within a month. Just keep in mind that the cruise must have plenty of available space or they probably won't drop it a lot. Plus, different cruise lines have different rules. I know for sure that Holland America offers the best rates booked within 30 days. This can be up to half off the advance purchase cruise rate. A very good deal. Call one of the non-rev travel agencies for more information and the rules of the various lines.