There are several websites that allow you to compare
travel insurance coverage from various companies. I've found that cruise insurance through the company that provides our home and auto insurance is often less expensive than the cruise insurance available through
DCL.
Think about what you want covered:
Is it only the cruise, or will you have non-refundable costs for transportation and/or hotel stays before or after the cruise? The insurance purchased through DCL covers only what's booked through DCL; I'm not sure what DVC insurance covers.
Do you have medical conditions that could flare up and require treatment? Some insurance will cover pre-existing conditions only if purchased within a short time of when the trip was booked; others will cover them for an additional fee or won't cover pre-existing conditions at all.
Will your medical insurance cover you if you need treatment during the cruise, either on the ship or in a port? If not, are you willing to pay out-of-pocket, or do you want insurance to cover treatment?