Great point. We're working on a render pricing estimator that allows you to upload a blend file and get an estimated price back. Until we have this, one way to see the estimated price of your render job is to upload your blend but cut the animation short. For instance, if your animation is 1000 frames, render the first 100 and extrapolate the price by 10x for a rough estimate. Then you can later render the rest by setting the animation in the blend file to only be frames 101-1000.