talking owner of apartment complex to sell property to me

[Cody Robison]

I found a 36 unit apartment complex near me that was up for sale a few years ago because owners wanted to retire. It's no longer on the market but same owners still own it.  How would you go about contacting them to entice them to sell? I know there names and a PO box but I don't have a direct phone number (other then office of manager on site). Is mailing a letter in hopes they will read it? Or get sneaky with property manager to get contract info. I tried looking online and have came up empty handed. I have a feeling they would be interested in talking about selling since I know they are wanting to retire. I have about 15 single family and Duplexes and ready to take on a bigger project. Thanks for any input. Also location is central Indiana