Based off my analysis on rents in the area and what I can do it for, I need to negotiate it much lower.  

They did a very detailed analysis on the housing market a couple years ago focused on evaluating the market since the great recession.

As far as estimating potential rental income, there are in depth resources you can pay for to get a detailed analysis, such as rentometer.com, or you can always browse rental listing websites for free (zillow, apartments.com, etc.) if you are just looking for ballpark numbers in your area.

I explained myself and attached a detailed analysis of the property.  

You may want to start learning the flip analysis through wholesaling before starting in flips, especially if you have no construction project management background.If you have cash investors that would JV, that can be a great way to learn if you're working with experienced people. 

Michael, in my experience, and I think you'll hear and read this from the majority of investors, the key is getting into a network of people that you trust and can work with you to help you take steps and be successful.I am, by nature, a deep dive research, analysis, and due diligence person.

However, I had entered numbers wrong in my analysis and now I'm not sure is a good deal.

Should you filter your analysis only based on Multifaimly-rent-to-price ratio? 

My analysis was simple: would I be able to charge enough rent to cover mortgage+HOA+property  taxes each month?  

You need to do a cost benefit analysis to see it is worth pursuing.