I remember reading a post where sanders used to come with a small mixed assortment of abrasives as shipped from Festool, but now they do not. The dealer might put some in of course.
I got assortments from Tool-Home as well.
I read in an old thread that Bob Marino will sell you a custom assortment to your liking, as opposed to the fixed assortments that Tom puts together. Of course, Tom would probably also do something custom as well.