In my market, I see broker pro formas all the time that have a 35% expense ratio which is literally impossible on a vintage building with a single boiler/hot water tank.

Be prepared to be shocked by the low, low price that rehabber will offer him to buy the gem. 

Not every investor has the time or desire to search and underwrite hundreds of properties to find the hidden gems to acquire.

sf we do go by the sq ft and what the comparables sold for. in mf here in the US and florida for mf there are many ways to look at it. you can go by sq ft per unit for rent, we also look at what type of unit mix is there, what the upside is, vintage of the asset, the NOI and cap rate...i live in boca.. welcome to florida yalla be kef

I think there are hidden gems but sometime stop and think outside the box.

There are lots of great single family housing stocks from the 1940-1950 vintage that sells for less than 80K (used to be 65K 1.5 years ago hah). 

You def made out on this little gem.

She sounds like a gem! 

I'm new to investing and am looking to start my portfolio with this gem!

@Mallikarjun Reddy Pateel as @Andy Eakes stated, you can look at the different OMs for expenses but sometimes those are projections or proformas from a broker vs actual expenses.There are report you can purchase for specific MSAs which have data from apartments by vintage and number of units.All of these should be a guide as the best source would be actual numbers from the seller and then you look for opportunities to improve income and reduce expenses.