3d print aluminum valve cover for car I am interested in 3d printing from aluminum valve cover for car SAAB valve cover

I am thinking of creating 3d scan and the placing order with i.materialize or similar online services. 

I am curios if this is feasible at all, since  I am interested in 3d printing functional part not just a souvenir. Also since 3d part does not have smooth surface, will sand blasting help without affecting dimensions?

Also what would be an approximate cost of 3d scanning and printing?

I really do not know where to start and would appreciate any directions.
This is a very large part. My estimate for the cost would be a few thousand to get this printed in metal, if not tens of thousands (assuming it even fits the maximum build volume of the printer, which is only 440mm on its longest axis).

3D scanning also isn't a very reliable way to reproduce parts, especially for something mechanical that needs to be precise. You can not just scan something and then print it like making a photocopy. A lot of manual design and reverse engineering work would be involved.