Getting an ARV with no comparable comps

[David White]

A potential seller reached out to my partner and said he wanted to get rid of his house. The seller owes 37k on a home equity loan. Its a 700 sq ft 2 bd 1 ba house on a 7800 sq ft lot. Besides his house and 2 others all the other houses on his street have been severely updated within the past 10-15 years. They're all at least 2 stories with some even having garages. So my question is how do I determine an ARV?