I go to home depot/lowes and buy 30 1"x4"s at 2.50 a piece and some 2" drywall screws, I make a simple crate 3" longer and 3" wider than the slate(inside measurements) so that they can go in/out easily. I like to use alot of 1x4s for extra support/protection but you could probally get it done with 20 . I line the crates with carboard before I screw them together.
As far as the table goes I save the boxes from some of my new tables and if the table is a Brunswick I can totaly dissasemble it and put it in all the original boxes. If it has a screwed and glued frame than I just box up the rails, pockets, aprons/blinds,legs and hardware then I attach a 1x4 on the bottom of the frame where the legs attach, line the table with carboard on the outside and stretch wrap the table and sometime all the boxes too.
So when I am done the entire table is crated and boxed up,looks very proffessional,and the customer is always happy with what they see.
If I dont have a box to fit a table part I will make one, the key is to have enuff cardboard,packing tape and stretch wrap to be able to box up everything. I charge 350-375 to do a crating job and it usally takes about 4 hrs to do all that by myself.