Depends on how many cases you order. Figure a least $1K to $2K a case if not more to have a solid block of aluminum milled out. In my business a plain case with just a few design changes can cost close to $350 to $500 per case for a box 12" by 8 1/2" x 6 1/2" powder coat plain aluminum with a 3/16" tick faceplate including name and rear panel lettering.
Happy Listening.
Happy Listening.