Looks to be a fairly well done recreation of a Virginia rifle which may have (originally) have been made by one of the Sheetz boys.
If no one recognizes the makers name then there is no premium to be gained from that. Maybe 40 or 50 years from now someone will trip over a rifle that I built and will have the same questions about the builder (point being, could have simply been a hobby builder that "flew under the radar" in the BP community).
If it's still in shootable condition, bore in good shape etc, then it's certainly worth the cost of parts.