hahahaha, there is no answer to this. This only invokes more questions.

What is the modelers skill level?
What Level of Detail will the model be at?
Are you using advanced Dynamics?
Are you using Fur?
Are you rendering in Mental Ray?
Are you using Final Gather?
Are you using Photons?
Are you using Dmap shadows?
Are you you trying for Low or High Poly?
Are you using Displacement Maps?
Are you creating large Shader networks?

This isn't even the first series of questions you need to answer..

...do you really want me to continue?
I could write about 3 pages of things that can change your model from a 10 min job to a 10 day job.