This is a few months late, but the main food court is on the 5th floor. Many shops have items that are as low as 25-30 baht. Around the food court are many inexpensive to mid priced restaurants. The 4th floor is also filled with mostly mid price restaurants. There are a few other places to eat on other floors including Tim Wo Han, but you were probably in the food court on one of the basement levels that has mostly western fast food restaurants.