Seller will not let me see the house before offer

[John Hixon]

Got a call off my direct mail campaign from a lady who is thinking about selling her rental and wants me to make an offer but she said I cannot see the house.  She is renting it to a family member and does not want them thinking she is kicking them out.  

The house is 1,500 sq.ft. 4 bed, 2 bath, built in 1974. To my knowledge she has not done any updates other than paint, carpet and tile. She said the roof is 9-10 years old. So, I would assume it is going to need a full cosmetic update. I estimate the ARV at $136,000 and she said that they have $30,000 left on the mortgage.

One GC I spoke with said that on a 1,500 sq.ft. house for paint inside and out, new flooring and fixtures it would be $12,000 - $15,000, if you went with granite and stainless steel appliances that would go up to $16,000 - $20,000.  

My question is, how would you make the offer or estimate rehab costs on a house you cannot see?  

Thanks.