Draw the offer or Walk away

[Shaleaha Flowers]

After initially rejecting my offer, a realtor got back to me today, asking if I could increase my bid by $1,000 to purchase a property. The owner of the property had started construction on a new project but stopped midway due to financial constraints. Furthermore, the owner had no permits, and it was unclear if any damages had been done during the construction process. While the owner was asking for $36,000, the house's actual worth was only $18,000, which I determined through the use of an Excel sheet and the tools provided by BiggerPockets. However, even though the numbers were not in my favor, I still find it challenging to determine when a deal is too good to be true or when it's time to walk away.  Any advice?