sorting classes in a list

Read up on the IComparable interface.

The CompareTo method will accept an "Object" as parameter, you will need to validate that it is comparing to the type you want to compare. (obj is StoreItem) then you can compare your desired fields.

For instance: (Not gauranteed to compile, but should give you an idea.)
public class StoreItem : IComparable
{
  private int _manufacturerID;

  int IComparable.Compare(object obj)
  {
    if ( obj is StoreItem )
    {
      return _manufacturerID.CompareTo( ((StoreItem)obj)._manufacturerID );
    }
    // else throw a suitable exception.
  }
}