OOP kids meals are pretty cheap - $4 - $5.
You can always ask for an extra side of something with your meal - that may be cheaper (and more toddler-friendly).
You can eat at buffets, where she'd get her fill of whatever she wanted.
But we just share - the food is SO good and the decisions are so hard to make that DH and I still share most of the time! (ie. "OMG this is SO good - you have to try a bite" or "wow - that looks REALLY good - want to switch?")
We get dessert for the table, too - each of us samples a little bit of each thing.

It's more fun that way.
Another idea - if you have a couple kids - we will split the kid-friendly entree if we want something they don't care for, then share other things with them, too.
For example, say we're at Coral Reef and my 4 year old wants mac & cheese. She eats about four noodles.

DH and I want shellfish - and they can't have it. So, I'll give the four year old some of my appetizer or salad, and then they'll split the macaroni and cheese.
We do this all the time with the kids - divvying up kids' meals. If you ask nicely, sometimes they'll even split it in the kitchen so that the kids get their own plates and don't realizing they are "sharing" - but we have REALLY light eaters and at WDW you can't really save leftovers, so it works great.