Purchasing a house with Attic Mold

[Alex Gordon]

Hey there, I'm a somewhat new investor looking to pickup my second buy and hold property.  I've just gone under contract on a duplex that fits my criteria and is in generally good shape.  I spoke with my inspector who told me the attic appears to have black mold in it.  It also appears the roof has no ventilation.  The roof also appears to be at the end of its lifespan.  

Any recommendations on negotiating from here?  Idealy the roof needs to be replaced, ventilation added and mold re-mediated.  I'm fairly DIY but won't do a roof.  Any cost estimates?  I just had a smaller roof done on a similar property for $8K so I'm guessing $10-12K for this one.    

I'm not out any money if I walk away so that is a thought as well.  I'd hope to use this as something that could benefit me in the end.  TIA