At the point you've got $60 or $70 in your cart and you are looking at shipping charges, it just makes sense to throw in some stuff for the cellar to get the free shipping.
Of course, don't listen to me. I just needed to pick up two 2 oz samples for someone else ($17 total) and somehow I got free shipping. 4oz for them, and then a pound of PS Balkan Supreme, a tin of Grousemoor, 8oz of St James Flake, etc. I have the wonderful ability to turn $15 into $100.