How to find the ARV of a multi-family

[M A.]

Hi all

I was wondering how to find the ARV of a multifamily that needs repositioning!

I want to make offers between 50% - 70% of ARV but I have no idea what the ARV will be. I understand cap rates, GRM and all that stuff but I have the feeling you just cant rely on that information. NOI provided by the seller is probably very unreliably as mom and pop investors hardly keep track of their operating expenses.

So my question is how do you find out what the after repaired value of an apartment building is since you cant really rely on NOI and Cap rates???