I haven't been able to find squares in sets but I have bought every size available here. My friend teases me about them but they work for me and that is what is important. I have 2.5, 3.5, 4.5, 5.5, 6.5, 8.5, 9.5, 10.5, 12.5 and 16.5. Now that I am more experienced, I probably wouldn't need to buy all of them but I've used all of them for squaring up and cutting blocks and my guild borrows them all the time for our Community Quilt afternoons. You can really power through a pile of scraps with the right sized square!