I buy the Grobet in specific sizes and cuts as individual files. Like Rich, I found that the sets were not as good a value, as there are some shapes that just don't get used. I like the half round, barret, and square (actually a triangle) to be the most useful. 4, 6 and 8 inch are used a lot. Some flat bastards and course cuts are useful too, but a heavy, large (10' or 12") square serves as well, and you get three sides to work with before you have to unload the filings.
Mike