Having trouble determining what my terms are on a deal

[Cameron Ysidron]

There is a four plex that came on the market in a great neighborhood in my area, which seems to be pretty rare in today's market. I'm really interested in taking this property on as my first deal, but I'm really struggling with defining my terms for how I need the property to perform financially. I always hear that you should have very well defined terms on what deals you will buy as an investor, but how can I define these in the first place?

For a little more background on the deal, it is listed for 350k which is high compared to properties in the area and of similar condition that were recently sold. I think that I can get it about 10% under market value for around 275k. I estimate 7.5k/unit in repair costs, and an ARV of ~350k. With all expenses accounted for with what I think are typically high percentages (vacancies 6%, PM 10%, maintenance and repairs 10%, cap.ex 8%, tax ~10%, insurance ~ 5%), and a pre-rehab gross rent value of $3k/month, I estimate that I could get $150/month in cashflow.

If all of the above proves true after doing more due diligence, I would need to find a way to come up with 90-100k cash to close and complete the repairs. 

I'm open to any advice on this property or my methodology that I've used, and I appreciate anyone who takes the time to respond.

Best

~Cameron