Grafs has a great sale on Nosler brand .22-250 brass right now. Do yourself a favor and by all new brass of the same maker. (the Nosler stuff is very good) The mix and match approach doesn't work if you are looking to get the kind of performance this great little round is capable of. Also second hand brass represents a safety hazard because you don't know its history.
People use to make their own .22-250 brass from many other calibers including the .30-06 but they did so out of necessity. These days, the .22-250 is a very common round with a huge variety of components available - no reason to fool around with brass forming.