I'm not aware of anyone making a .40 Super barrel any more. Pacific Tool & Gage did the original reamers; I just emailed them a few weeks ago and they can provide the reamer and a headspace gauge for about $200. There are some incompatibilities between the .400 Cor-Bon and .40 Super chamber drawings I've found online; if they're both correct, you'd need to start with a .40 S&W barrel.
Starline has brass, and loaded ammunition is available from a few places.
The .40 Super gets up into midrange .460 Rowland muzzle energy without the necessity of a compensator. I waffled for years on the Rowland, but I could never come to terms with the fugly comp.
I have a bag of brass, and I'll be able to get the barrel in a few weeks. And then I'll be saving my shekels for the reamer and gage.