Iris,
Character meals can range from reasonable to expensive. For example you will find a family of four spending anywhere from as little as $60 to as much as $185. It all depends on the meal, the location, and the characters. As for quick service dining, again you do get a range, but I usually budget for myself about $30 for a family of four (all estimates assume 2 children and 2 adults).
So what meals are you considering? Some of the more affordable Character meals can be some of the most fun.
Donald's Safari Breakfast over at the Animal Kingdom is on that lower end of the cost spectrum, and I love it. Why? The food is not bad, and the setting really gets you in the mood for a day "on Safari". It gets kids excited and fueled up, not only physically, but emotionally.
The more expensive ones can be great too. It is all about what you are looking for!
Feel free to go to my bio page and ask me a question directly. Give me some information about your dining preferences, and I am glad to make some suggestions!
Have a magical (and delicious) vacation!