Air conditioning unit for 280SL

I have a 1970 280SL that originally came with "factory air conditioning," but the under-dash unit was stolen before I acquired the car 20 years ago.  Has anyone replaced one of these and if so, from where did you source it?  I live near the MB Classic Center, located in Irvine, CA, but am assuming they will charge an astronomical price for the unit.  I'm also assuming I would have to replace the other air conditioning components that are under the hood.