Negotiations and Cap Ex

[Chase Gruening]

I am getting close to getting a contract on my second multifamily deal. I am having trouble estimating a accurate cap ex and we are about 20k apart on 330k counter offer. The deal involves 3 separate duplexes (6 total units) all next door to each other....

One of them needs a new roof. The total rents can be raised to the low end of the market about $350 total. AS IS it will cash flow about $150 per door with the worst month of expenses and 5% vacancy rate (great location), fully rented right now.  I have proof of annual expenses from water, tax, insurance companies that I used to calculate expenses. I have only estimated 1,000 per month in my cap ex (3,000 total) per year in my calculations. 

I know this is not very accurate and would like opinions on how get that more accurate. More from experience the a general rule of thumb. These are good properties in above average condition. All updated. 

Also in terms of getting closer in negotiation. Any ideas or suggestions in order to get closer to a contract?

Thanks.

Chase