After 9/11, it used to be that you could expect to get a discount when you booked a cruise online. For seasoned cruisers, it made some sense. For first timers, it made none, as price usually indicates the desirability of a cruise. The lowest price generally indicates that that ship or itinerary (or both) may be less fulfilling, hence a less than satisfactory cruise experience.
If you think about it, the actual cruise fare is only a small part of the total cost of a cruise. When you lump in airfare, pre and post cruise activities and accommodations, other purchases and expenses, the base cruise fare should allow for some elasticity.
Today, most of the cruise lines (Carnival, Royal Caribbean, Celebrity, NCL etc.) have adopted a “standard price policy” across distribution channels so that you are going to pay the same price, no matter where you book it. That being the case, you should look for the highest level of service that you can find. Online agencies are notorious for offering discounts without service and seem to have lost their competitive edge.
Your best bet in the current environment is to find a local cruise professional and book it with them. They will do the do-diligence to make sure that everything works for you. They will make sure you get a better price if the price drops, or an upgrade. They can advise you of the appropriate ship and itinerary, and so on.
BTW, I do not sell cruises and have no basis, other than trying to give the best advice on the topic. You should follow every channel available to you and make a decision accordingly. Don’t just book it online, because at one time you could save some money doing so. Such is not the case now.
Whatever you decide, have a great cruise.