Since you are renting a house and budget is an issue the Dining Plan probably wouldn't have been cost effective for you anyway. With a house you will be able to have breakfast there in the morning and possibly even dinners a few nights to save some money if you need to.
The dining plan is a good expense if you plan to eat at a sit down restaurant each day. I went 2 years ago when the dining plan was added for free and my 2 daughters and I had difficulty using all the credits it offered!
Unless you are a "foodie" and/or want to do several character meals you can probably cut your food budget by having a big breakfast in the morning at the house, bringing some snack foods with you to the park--like crackers, nuts, trail mix, beef jerky, and juice boxes and your own water bottles, and then having a big lunch around 1 or 2 in the afternoon. We find when we do this we just snack if we are still in the park at dinner time and then you can have some quick and easy stuff on hand at the house to make dinner when you get back. The counter service meals at the parks are very generously portioned. We usually do breakfast in the hotel room, counter service for the rest of the meals and splurge on one or two character or sit down meals. It is much cheaper than the dining plan would be.
Have fun and let us know if you have any more questions!