Express shipping costs are calculated by the size of the package. Instruments ordered without case (your selection) need a much bigger cardboard box to guarantee a save shipping. This enormously will increase express shipping costs. Upgrading to "buy as a set" will downsize the cardboard box dimensions and costs a lot. In consequence the price difference between our two purchase options becomes smaller. This means that you could get the additional set option case a for only a few Euros more all in all.