Well then you are not refering to a cast part, you need a machine shop, especially a one off piece, castings are for tens, hundreds and thousands of pieces in order to be economical, barring artisian castings of course.
If you PM me I will give you my fax number, send the drawing and I can have quoted. If you are outside SD, well then you need to look local in your area, Santiago actually has several decent machine shops as well.
g'luck