I didn't purchase the insurance through them, but I did look at it on their website.
I believe the cost of the insurance is determined by the cost of your trip and indirectly by the number of people and the duration.
In other words, two adults and two children aged 9 and 11 would pay a specific price for insurance on a 7 day cruise with a total cost of $3,500. The same family would pay a lower price if they were on a 7 day cruise and the total cost was $2,000.
I'd suggest just going through one of the online quote sites for that company and then try a different company for a comparison.
hope that helps