Apartment intercom

[keith gigabyte]

Did a quick search for apartment entry systems. I see prices and options are about as varied as you can get.
I have a 3 unit apartment building and the owner wants simple Intercom to each unit and each unit able to “buzz” up visitors.

any inexpensive ideas?
thanks

 

[electrofelon]

I think the hard part is installing the electronically controlled latch/lock. I don't know much about them, but the few times I did intercoms, the owner skipped the unlock function because his door was an old antique non standard thing and it seemed like a huge hassle. Perhaps one of those magnetic locks would be easy to retrofit.