Using November
UT ticket pricing as a rough guide, a 7-day ticket is about $700. If cost of renewal is $1100, then the OP would only need to 'cover' $400.
If they go just once and normally eat 1 table service each day, where a table service buffet runs $55 per person +tax, then an annual pass will save $5.83 per person per meal. ('Ohana as an example.) If OP is a family of 4, that's $23 per meal. Over a one week visit, w/1 table service meal/day that's $163.
The alone brings difference down to $237.
If OP only ever stays at DVC's, then they won't save on the hotel. They might make up some of the $237 in merchandise discounts, but probably not all $237. There is also $10per ticket AP discount off MK Christmas party tickets.
And that is assuming the return trip is in November. If their return trip is
next year, odds are high that the price of a 7-day park ticket will go up!