Buffets are a deal for 2 year olds! We've been when my 1st DD was 18 months, again when she was 2 1/2 and her sister was 8 months and eating table food, and again with her at age 4 with her 2 year old sister and 10 month old brother who was also eating table food....You are never charged at a buffet or pre-plated style meal (CRT breakfast, Epcot PRincess breakfast., etc).
If you order food from a regular menu/kids menu, you are charged accordingly (fair enough!).
Enjoy...a little bargain at WDW.
Hope that helps!