It actually depends on who is ringing you up. You can get the Rice Crispy treats, which are $2.49 (I think) and the ice creams are about $2.50.
At some of the resorts they will let you get things not stated on the plan, so you may be able to get something with a higher value.
That said, when looking at the value of the dining plan you should base it on what you 'would' order not what you 'could' order. That will give you a much better idea of the value to you.