I would bring stuff to have a quick breakfast in the room before heading to the parks, like get a box of cereal and some milk. We did this in July when we didn't go out to breakfast, in order to save some money and get to the parks early.
Here are some cheaper TS places by the BW:
-ESPN Club (burgers, sandwiches, many options between $11 and $15)
-Beaches & Cream (cheap burgers and sandwiches...a single cheeseburger is onlt $8.99)
-Big River Grille (prices comparable to ESPN Club for sandwiches, burgers and salads; kids' meals as posted on All Ears are only $4.50)
In the parks (these are TS places that have cheaper options, as well as expensive ones):
MK: Plaza Restaurant
DHS: Mama Melrose (dinnertime); 50s Prime Time (lunchtime); Sci-Fi (lunchtime)
At Epcot, the CS in Morocco is VERY good and definitely well worth going to. You can get certain things there for under $10 and the food is excellent. In fact I have heard from many folks that the CS restaurants all over the WS at Epcot serve some of the same food for much cheaper than the more expensive TS places. For example, Fish & Chips at the CS location in United Kingdom in the WS is MUCH cheaper than the same entree at the TS location. Same food, maybe a slightly smaller portion, but just as good quality. Keep that in mind for Epcot.
At AK, we really loved the Flame Tree BBQ which is a CS place, but is very reasonably priced and delicious food.
At AKL, you could enjoy the same famous zebra domes as they serve at Boma from Mara, but for much cheaper than dining at Boma, if you really want to treat yourself to one on a budget.
Enjoy your trip!! Remember, like you said, on the next trip after this one you could indulge some more and enjoy things like character meals and maybe some signature restaurants.