The easiest way to build store points quickly is to go to the high point challenge in freestyle mode. Once you are driving, try to pull of as many backflip combos as you can on every jump. Once finished with the round, you will receive half the
stunt score in store points, sometimes even getting 100,000 store points in only a one minute run. The dirtbikes are slightly easier to accomplish this with. To get fast and easy store points, go to single player mode. Do freestyle mode for
about ten minutes and you should have about 1 million store points.