The first place I check is the Vacations to Go site. This is where I narrow the choices to one or two different cruises. I love this site because it's well organized and easy to use. It lists cruises from all over the world, prices and more. It even converts to Canadian dollars.
The one thing you have to realize is that many of the sites on the internet (including Vacations to Go) are from the United States and therefore not covered by TICO.
In Ontario, The Travel Industry Council of Ontario (TICO) administers an industry-financed travel compensation fund. This means that if you buy travel through a registered Ontario travel retailer and that retailer, service, air or cruise line goes bust, you are reimbursed if a refund is not otherwise given. If you don't live in Ontario, check your province or state to see if there is similar coverage offered.
In my experience, many Ontario travel agents will match or even beat the prices that I find on line.
The next step is to find an agent that will do this and give travel reward points. I chose the local Cruise Ship Center and not only did we get the best price, TICO coverage and aeroplan reward miles, we also received personalized service. Of course we paid with our travel rewards credit card.
So if you are dreaming of a cruise, take a few hours on line, call around and soon you can be sailing the bright blue seas.