Yeah, some breeders may have breeding records available where you can trace unregistered purebreds back to registered animals and draw some blood samples to do DNA testing but the whole process is very costly and probably not worth it as unregistered animals bought at the sale barn are probably not the cream of the crop from that breeder.
If you are looking into getting into the registered Hereford business which right now is a good time as Herefords are selling well to both the commercial and purebred breeders you may want to find a Hereford breeder in your area and see what they have for sale. Not sure where you located in comparison to Red House, VA but Knoll Crest Farm is a very good Hereford breeder in your state. Rock Mills Herefords in Castleton, VA is another reputable breeder. Not sure what kind of budget you might have but Knoll Crest has some of the top end Hereford sires in the breed so there is no doubt you'd get a productive female from their program.