Hi, Camille! Planning fa Disney Vacation for 7 people can seem like it would break a budget, but with careful planning, you can do it!
Disney runs special promotions you should watch for. I have marked a page
HERE that lists dates where you can stay at a Value Resort for a little as $49 a night! Each room sleeps up to 4, so you would need 2 rooms. Although you said transportation is not a problem, Disney does provide FREE transportation to and from the airport as well as throughout the Disney property.
To save money on food, I would suggest keeping some snacks in your room. Having bagels or breakfast bars on hand not only saves you money, but will save you time in the mornings allowing more time for Disney fun!
For the parks, toss some refillable water bottles in your backpack and some snacks to munch on. I even carry some juice boxes for the kids which, again, saves money and time from waiting in line every time they need a drink!
Have fun planning for your vacation!