Can they do this?

I am living in a co-op building in Hamilton, Montana. I enjoyed my stay here because of the people around me who were so approachable. In my co-op, there is a move-in-move-out deposit of $2000 for possible damage to the building. The deposit is refundable if no damage occurs when you decided to leave. However, they have added a non-refundable $2500 fee in addition to the move in or out. Can they do this? Is this legal? I do not think I can afford another $2,500 for this one.