I have found 6 or 7 multi family properties that I can't seem to nail down contact info for. I'm typically EXTREMELY good at digging it up. 

I'm using Realist to track down the owner's name/address. Most of them are held in an entity of some sort. I'm then going to the state website (where the entity is registered) and digging up the names of individuals. Then using a service to get a # for the name. Problem I'm running into is things like the mailing address being a tax office, or attorney, and even a liquor store. I've called and they don't/won't pass along a message. I could just mail the tax address but I'd rather leave at least a voice mail. I've used Linkedin and other sites to attempt to contact individuals with no luck. 

Do you think an agent would accept something like $500 cash if I'm able to turn it into a deal? I'm looking for properties to hold, value add/rehab, and potentially sell off market. (If I were to sell it off market I imagine that the agent would want a larger cut) Any tips?

Also these ARE NOT fresh expired info. These are anywhere from 6 months to 5 years old.