While I have been on The Magic, we did not use points. The disneyvacationclub.com website has the point sheets in the member section. (the link is goofy, otherwise I would give it to you).
Unless you have a lot of points, or plan to bank and therefore not be able to use those points in a two or three year span, I would suggest paying cash.
It also depends on what type of cruise you would take. I will never be able to take anything other than the 7 day Magic.
It is a great trip, but there are a lot of cash specials so look for them first. If you have a ton of points, go for it.