That would depend on whether you were intent on duplicating the exact look of the SF body, or could settle for something simpler.
A 12" piece of 303 SS goes for about $40, unless one can find it cheaper on eBay. A real plain tube would have to be at least double that amount. If you tried to replicate the SF look, then the cost would jump considerably, maybe to as much as $200 to $225, depending on the time involved.
As I said, it just costs a bit.