No comps! What to do?

[Fred Hamilton III]

Im in the process of getting an offer together for a seller whom has not put the property on the market yet. I have walked to property,taken pix, and also had repairs estimate done. The issue i have is the REA attempted to pull comps but there isnt anything in the subdivision sold in the subdivision in 6 months. The REA sent over homes similar that are in the subdivision and the property adjacent to the home. How can i use this info to make a reasonable estimate of what the value should be? Any input or help would be greatly appreciated.