the simplistic formula of, for example, buy for 100 rehab for 50 refi at 200 is way off and understates the costs involved. 

I am using formulas found on BP and I understand they're just a baseline but it will take some time to learn how to squeeze those numbers depending on the deal. 

there wont be much if at all.I swear so many are just not including expenses nowadays in determination of you know...Profits.Isnt there an envelope formula,  something like this$4,500 times 60% less piti equals income.40 % being expenses,  good ballpark rule.

If I really like the property ill go as low as 9%CoC = (Monthly cashflow after expenses*12 month/total cash invested)*100%So if all in your investment is 18,000 including down payment and closing costs, your CoC is 10%$150*12/18,000)*100% = 10%  with that formula I would be cutting it close about 9.5 percent 

Your numbers are valid for your goals, so I'm not telling you to change your formula. 

They look at a lot of formulas like debt to income ratio, your credit score, your cash reserves, etc.  

I met Jake from the business I owned, and we decided to partner.There is no formula.

The danger in building your own model is that it's so easy to forget important items or have incorrect formulas.

How does one calculate a good deal for a new development project, is there a formula for this?

I do echo your question about whether other folks here have a more formulaic approach to determining the class of the neighborhood.