theres a few things I would consider with this that I feel may not be as helpful as you suggest. the first being you only get the 10% off the price of the cruise, not port fees and taxes. I could be wrong but did you include that? second, being Canadian, getting the gift cards to save money is not really an option. we no longer have targets and even when we did they did not sell Disney cards. also, while the cost may still look good to some, our dollar is at about $1.33 to the u.s. meaning we need to add 33% more to the cost of the cruise. not cheap at all. I can book with other lines in Canadian funds and that makes it way way cheaper.
for example, I can book the oasis leaving feb 26, 2017, in a Superior Ocean View Stateroom with Balcony, 232 sq ft compared to the dcl sailing of 241 sq ft (I think) for 2A $2503 CANADIAN. so dcl, with exchange rate, using your numbers with your discounts ($2850 X $1.33) I will pay $3790 Canadian where as the oasis is, as noted above, $2503.
I will save $1287. before anyone starts talking about having to pay for soda, that would cost me about $110 so I don't even think that's worth mentioning.
thank you for your ideas though, i'm sure it will help some.