I'd suggest take photos and see if any sign writers/sign makers etc can copy them. Other than that you'll never buy them new (NOS) now unless you were better than very lucky... Looking closer at them I think they look to have a fade from orange into yellow, might be better off to get a good custom painter to replicate/airbrush them for you. A check in the yellow pages in your area should uncover someone who might have the nous if you've got the time and $$$.

Regards,

Dave.