How to make initial contact/offer to off market MF owner?

[Reno Puente]

I have been looking around town for some "not on the market" apartment complexes and have found a few. These are owners that didn't even know they would like to sell. I have convinced them to maybe think about it and call me back. How do I figure the amount I should offer? What do I really need to see from their rent rolls and P & L (or something else)? For example, I found a 24 unit apt complex that charges $700 for 12 units and $550 for the other 12. The complex is a C, at best a B-, but has room for improvements and rent increases, but I did not tell them that. Any help is greatly appreciated.

Reno (1st time MF buyer)