Bulgaria did not make an SKS. It could have been issued to the Bulgarians, but will be Russian in origin. I am also unaware of an issued scope for a Romanian or a Russian (as the Bulgarian rifle is not actually made in Bulgaria) SKS. Finally, East German SKS carbines are absurdly rare. I have heard unsubstantiated tell of at least one in Canada, but have seen no proof. There's something like under 70 identified East German Karabiner S rifles in the entire United States, as well. If you have a line on an actual Kar.S in Canada, which I will be honest - I doubt, you are one hell of a lucky guy. The seller can ask pretty well what he wants, in that case.
Frankly, this sounds pretty fishy. With what I know about the SKS, which is perhaps a bit more than the average bear, I wouldn't offer anything. Get some pics, share them with us if possible. I'm very curious.