I have not heard anybody complain about the Sportsman's Guide Knight Vision rifles.
I would imagine if these rifles were "blemished" the Sportsman's Guide would list it as such in their advertisement. As far as the price I have no idea why they are so cheap. I have heard they are built very well, and at that price I don't think you can go wrong.
These are new rifles so I believe they carry the same warranty as all other Knight rifles.
The forum member Pluckit purchased a Vision from Sportsman's last week and last I heard he had no complaints with the quality of workmanship or condition of the gun. I do not know if he has shot it yet. There are other members on here that own Visions as well and I have not heard of any major complaints. Good luck with your purchase.