it doesn't matter on how high the quality is, what matters is the lighting and the level of realism. You will notice in many CG films they avoid having any shiny objects, and in many ways they 'Bake the lighting into the textures' or use self illuminated textures which will reduce the rendering times.
You are just like many of us, we believe we can create incredible things, well its easy to talk about them but my friend the planning and the organisatio involved in doing them well thats another story.
a 5 minute render can take anywhere from 5 minutes to five days, 25 frames are needed for a second in the UK, could be 30 in your case? But 1 frame depending on the quality may take 10 seconds to ten minutes.
Now you do the maths, with an animation taking such a long time to render, you need to plan everything. What you need to do is to watch a DVD special edition of a CG film and look at 'the making of' then you'll realise whats involved in getting your project off the ground.
Plan, Plan, Plan, Plan, Plan, Plan, Plan, Plan, Plan, Plan, Plan, Plan, Plan, Plan, Plan, Plan, Plan, Plan, did I say plan?
hope that helped