I need a :90 explainer video with simple animation

I need a video that would basically be an explainer video done in all type.
The words would need to animate/transition very simply from frame to frame.
Across the bottom 20% of the screen, I want an animated line drawing that continuously draws the skylines of probably 20-30 cities over the course of the video (the skylines are basically one long continuous scrolling element across the bottom of the frame for the length of the video).
Can you please know what you think this would cost and how long it would take?
Thanks,
Rachel