After a disappointing experience, thus less-than-satisfying meal at Garden Grill last December, we stopped by the food court at ASMu to split a double cheeseburger. We asked for another bun and they gladly gave us another one and when we went to pay, the person at the register said that she had no clue how to ring up an extra bun so she just gave it to us. I think that happens often, but I've heard that they officially cost around $ .30. However that was a year or two ago, so they may have gone up, but I can't imagine that they would be more than $ .50.