Costs for a Characteranimation

Hey guys. I received a commisioned work recently and now have to tell a price to the client. But as i do not have much experience in projects like this, i wanted to ask you what a realistic price is.
How long would a professional need for something like this?

It is about the modelling/texturing/rigging a character like this: http://www.blendswap.com/blends/view/14445

There will be an animation with a lenght of about 15 seconds! Nothing to render because it will be used in unity.

Would be great if you could help me! :wink:

Best wishes