Brenda:
Although the parks have lockers for cooler storage, you can leave it in your car and simply leave the park for lunch, no problem! Just make sure you have your ticket for the return. The only park I don't recommend for this: Magic Kingdom. Cars are parked at the Ticket & Transportation Center via a ride by monorail or ferry (and possibly a tram once you get to the parking lot). I don't think the time out of the park is worth the cost-savings....
Another option: bring a cooler
into the park as long as it isn't
larger than 24" long x 15" wide x 18" high. OR consider what my family did on a recent trip: put lunch in plastic disposable containers in a backpack. We "picnicked" by the water in front of The Plaza Restaurant at MK and then used it to hold our souvenirs!
Speaking of souvenirs....As for money in the park, that's a toughie. Our family has a Disney Visa and uses the rewards on our trips: a great tool for budgeting. The kids save money in one of the large plastic Coca-Cola banks from Cool Zone at Epcot and divide the money
equally, about $50 per trip. But since everyone's budget varies, click
here for a sampling of items and prices of fun souvenirs you'll see on your next visit!
As for food prices, Disney is no different than say, the airport, but the quality and customer service are three times better! My family members aren't snackers, but if yours are, count on spending $2.09 or so for a soft drink, $2.89 plus tax for soft serve ice cream at Aloha Isle (my favorite, but I opt for the DoleWhip float for $3.99), or $3.95 plus tax for a fruit bavarois at Boulangerie Patisserie (you guessed it, another favorite).
Wishing y'all a magical vacation!
Whitney