I have a set of the cheap Summit ones and have used them effectively. If you are really cheap or just in a fix then just cut a vertical slot or two in the threads of a bolt and use that, you'll get the same result. For the price of the Summit ones, it's probably cheaper just to buy them than make your own....
This^^^. For $10 the summit ones are nice to have. But if you are missing a size, a grade 8 (preferably) bolt and dremel cutoff wheel will create the exact same thing it about one minute.
