I have been watching ticket prices online for Amtrak Zephyr from CA to IL. I was told that you should book in advance for cheap prices, but I am noticing that the price is almost cut in half if I want to travel the very next day. Usually the prices are $700-$900, but some days it's around $450. Is there a trick to getting a good price? When I called them, they only tell me prices depend on availability. I'd be willing to travel the next day if I knew I could save $300.
I think the drop in prices with 1 day to departure is self explanatory. Revenue management. An empty roomette from CA to IL is a loss of potential revenue that can't be recovered once the train has completed its trip. Hotels will do the same thing; drop prices for rooms that night or the upcoming weekend if they have surplus rooms. An empty hotel room makes no money.
With the constant delays on the California Zephyr, they may be getting hit with cancellations and fewer room sales. So, they are dropping prices to a lower bucket one day prior to departure to try to sell some of the empty rooms and roomettes. Unfortunately, Amtrak is not doing this on the NEC, but buying tickets at the station (or with the Amtrak smartphone app) for the next departing train is routine on the NEC.
As for "buckets", that is the travel industry term for seats (or rooms) sold at different price levels. There may be so many seats available at the lowest bucket, then once those are sold, then there are so many seats at the next bucket price. Airlines have been doing this for decades. It is all about dynamic demand pricing to generate the most revenue. Amtrak generally has around 4 to 5 bucket price levels.