Its my understanding that instead of say, purchasing Action Essentials 2, you could make your own by filming said effect (lets say exploding puffs of dirt) in front of a black/green etc screen. Is that all there is, or is it far more complicated like everything else.
Filming your own assets is often a good idea, but doing it well requires a lot of experience and planning. The reason that people sell stock footage assets like Action Essentials is that it's often much more cost-effective to buy it than to shoot your own. I encourage you to learn how to do this kind of thing yourself, but don't expect it to be the efficient approach until you've learned and practiced (and failed) a lot first.