@Carlos Rodrigues
I agree with @Account Closed about finding out Sellers motivation.
I have a few questions. How long has the property been vacant and why? What conditions is it in? How much Rehab will be required? Is the basement legal (appraised)? How did you establish rent rates? Did Seller provide past rent rates? Or, did you estimate based on market rates? What are expected operating expenses? Gas leak! Can you covert to all electric? I do have more.
Sorry for all the questions. But, these are things you need to answer to be able to negotiate effectively with the Seller.
This is an income driven property acquisition. It must be able to cash flow after you purchase it. The Seller should understand that. Since it is not currently providing income then the purchase price is extremely negotiable. And as suggested "Seller Finance" might provide a win - win situation.
Hope this helps gets you going in the right direction. :)