I had the all the flanges water-jet cut from ½” 304 SS.  I had a buddy do it for me, material costs were ~$80, and it took ~1/2 hr on the machine.  Water-jet machines can range from $100-$150 / hr. from what I hear, so that should give you an idea on cost.

Here is a .zip file with the AutoCAD drawings for all the flanges.
 

flanges.zip
 

If you need a viewer for .dwg files, download Voloview express.
 

http://usa.autodesk.com/adsk/index/0,,837403-123112,00.html
 

All the lines are closed plines, which means they can directly import them to the CNC machine.  This will save a lot of time for whoever cuts them.
 

The only one without the holes is for the WG.  I didn’t have the proper measuring tools for the funky hole pattern at the time. It’s easy to drill these using the WG for a jig.
 

The turbo inlet flange has small holes that will have to be drilled through, or tapped. I am just using through bolts. Other than that the holes are perfect throughout!