Hello. First of all I would like to guide you about what would you need to do something similar. As an expert in 3d and character animation, I am going to explain you the process (more or less).
This is a very complicated work. First, it is necessary to have a good Script with all details, the second would be to have something called Layout. With Layout you create an animated storyboard from Script, justo to have all the angules of cameras, timing, expresions (so important because is so dificult change something in the middle of the process). Third, model and textures of all the elements like backgrounds (or do the animations on videos recorded), characters. Once you have the model of the character you need to create a rigging (controls) and skinning (for the animation). Now you have all the elements and characters is time to create a basic 3d Layout (like the 2d Layout). The animator would be polishing the entire animation in steps (blocking, curve and polish). The last is lighting, rendering and composition. Rendering take a lot of time, so, you will have to be patient.
This is a very complicated project for everyone, be aware of people who say to do this. I can do it, but notice all the freelancers who say to do it only do architecture. This is other world of 3d. It is necessary spend years to learn each process and of course is necessary to know basic concepts like drawing, painting, sculpure...
This could take 3 to 5 month, depends. and the price 8000 USD