C# static member class with members

I have some classes with a static member:

class BuildingA{
   static BuildableComponent buildableA;
}

class BuildingB{
   static BuildableComponent buildableB;
}

This static member has it's own members:

class BuildableComponent{
    int cost;
}

I would like to be able to manipulate the members of the static via the BuildingA and BuildingB classes, eg A.buildableA.cost and B.buildableB.cost - the way I've described it doesn't quite work, but is there a way to do this?