All of those factor in. Lets say for example, I have a ball that I absolutely love and its discontinued (this has happened to me) and something happens to it, I'm trying to find a ball that will give me the same shape, especially in how fast or slow it responds. Eventhough companies discontinue balls, if it was successful, they rarely completely go away from it unless it isn't cost efficient. Because of these reasonings in todays game, I always recommend buying multiples of a ball you love. At one time I had 6 Radical Reaxs, 8 Hyroads, 4 IQ Tours, 3 Tour Nanos, 3 Tour Pearls. But if you like a ball and it rolls good for you then youll see the return on your investment.