I think you will find most of us are in the same boat, financially, we are all looking for ways to get the most bang for our holiday dollars!
One of the first things you will need to pay for in full is the Airline tickets, so unless you have enough points already - you will not have enough time to earn them.(but you will earn heaps for next time

) Everything else you can just put deposits down and Disney is pretty good about refunding in full until about 45days out. (not sure exactly)
I started planning our trip about this time last year, as a family of five we got a pretty generous tax return, so I squirrelled this away and started adding $100 per week to it. This, coupled with this years tax return should cover our trip.
We also had some NRMA (IAG) shares that we sold, - remember when they floated the company and everyone got shares - well we had been sitting on ours for the last 10years and I decided that they werent going to make us millionaires - so sold them for about 4k.
I had budgeted our trip when the $ was around 85c so seeing it climb, only made our holiday cheaper, when it was around 95c I changed the money I had over to a Travel card - (who knew - it woud rise to $1.10

, but it could easily have fallen back)
The travel card has been great for paying things online (it works just like Visa debit, but is in US currency, so no conversion fees)
I have prepaid as much as I can, we have free Disney dining - so we shouldnt need too much spending money, our annual leave pay should cover this (we wont have the usual expenses that our money disappears on - groceries, petrol etc) - although I am told shopping is cheap - so will use the credit card a bit if necessary (up to $1k - really dont want to do this)
Meanwhile we have had a pretty frugal year, although we have had two children with orthodontic treatment and catholic school

and we just had to replace our oven - there has been plenty of things we could have spent that money on, you just have to make it a priority!