Requires some research. There is no single answer. Sometime you can find an agency that has a group booking for the cruise in which you are interested. As a part of the group, you may be able to access these great rates. There are group bookings available on this website; do some research. Nothing beats having a reliable and efficient travel agent. Lot's of reputable TA's post here. Be sure when comparing cruise pricing that you are comparing apples to apples. Some agencies don't quote the total price of the cruise; adding taxes, fuel surcharges etc after the fact. Always ask for the TOTAL price, and be aware of other charges such as "document handling", cancellation charges, etc. Did I mention, do some research!