Try the set with the three tips and the cables, plus a plastic wallet to keep it in. It's a lot less expensive, and you get a start. Otherwise, my two cents is, if you buy them separately, the most common sizes that I have used are 4.5mm/US 7, 5.0mm/US 8, and 9.0mm/US 11, since I've done mainly scarves, mohair, and bulky. I'd personally get 2 of the shortest cables and 2 of the longest. (To be able to do smaller items like hats and sleeves, and Magic Loop for even smaller items.)
Your own mileage, of course, may vary.