For an unknown brand coupled with an incomplete component group, my offer would be low. Under a $100 for sure. And, should you get the bike, it might take years to identify its pedigree.
This Geoffrey Butler, a frame set sporting wonderful workmanship, took me four years of trying to identify. Finally, a fellow forum member came through with a positive ID. Suddenly, my unknown frame set went from near worthless to worth a lot more. I should add that finally determining what it was/is was worth the wait...