The prices at RFC are pretty much in line with every other TS on property. It is still a lot for a burger, but you are not going to see one for much less until you go QS.I used to love rainforest Cafe at Disney Springs. But I have since vowed never to return. A burger and fries is $20, no thanks! I actually like the ambiance it's a fun thing for lunch on the first day or a free day.
As far as animal kingdom. At one point, it was struggling no one went. They used to go as far as begging people with signage and having cast stand outside directing them to rainforest.
RFC Basic cheeseburger $18. Beastly burger $22.
Burgers at Restaurantosaurus $23. (includes drink and sundae)
Plain Cheeseburger at Beaches n Cream $17
OMG Burger Raglan Rd $22
Edison Burger at the Edison $23