You could look at 2nd hand but make sure you know beforehand what length steerer you need taking into account the stem clamp depth and any spacers to give you the height needed.
Certainly older Principia frames took a straight 1" fork (unlike the later ellipse variants) so that might be a source, I'd also check on the LFGSS website as there's huge amounts of stuff for sale there.
1958 Carlton Super Python
1990's Gitane VITUS GTI Triple Butted
1996 Raleigh Titanium Special Products Division
2007 Specialized Globe Pro
2007 Specialized Globe Expert Ultegra 6700
KTM Strada 6000 Carbon Dura Ace 9000