how to determine price on a negotiation on a flip, buy and hold

[Justin Heitter]

Hello everyone, I bought first duplex a couple months ago(in  coeur d  alene idaho) for a house hack and down the the block is a very dumpy duplex that is vacant, has a bad roof, siding has holes in it, garage doors are bad.  I always drive by it and i wonder if I can buy the place (its not on the market). I looked up the property on the county records and found out who the seller is, he lives in California and is a RE agent.  

Although not having a clue what I am doing.  I called the guy and told him I was interested in buying the place from him.  He said he had insurance and it lapsed, and ten days later he had a horrible flood/leak in the house.  A local contractor told him it will be $70k to fix it. And he said he didn't know what he was gonna do with it.  If he was gonna sell it or  not.

He didn't tell me this... but I found out some details about the property.  In 2005 he paid 219k for it .  One unit is a 4 bed 2 bath, and the other unit is 3 bedroom 1 bath.   (I could probably get $1200 for rent after its rehabbed, thats what I am charging for my 2 bedroom down the block). The other unit is a 3 bedroom 1 bath. and could probably rent for at least $1100.  

Total Rent $2300.  

Total Rehab $70,000

After Repair Value $250 possibly more 

My offer Price ???????

What would you guys offer considering what this guy has on his hands.