304L stainless will run +/- 3 bills/ft depending on o/d-i/d.
If you have free access to cnc machinery and don't mind the work you can save half or more. But you'll also have to shell out for specific cutters to cut through 304 and also hone it up nice, the stuff is hard. They won't know what you don't tell them.
If you have to pay labor it's easier just to buy one and know that it will fit with zero errors. They may know, registration may or may not be required.
For the record, I don't own one and never will. But I do know about metals, thus the info.
"What if the American people learn the truth" - Ron Paul