Alternative to Separate Electric Meters for Multi-Family

[Jesse Smith]

I own a 3-unit property.  It was originally an old house, and it was divided into three units.  Only problem is that Unit 1 and Unit 2 are on the same electric meter and breaker panel.  The circuits are clearly divided between the units within the breaker panel.  

I had my electrician come out to discuss the situation.  He estimated $4-$5k in expense to properly install a third electric meter and a new breaker panel, and then to separate the circuits into the new panel.  

I'm curious if there is a simpler solution.  Is there a device that can read the electricity used by each circuit, so I can bill back the electricity, based on consumption?  What I'm picturing is a device that would have clips to attach on each circuit in the breaker panel for Unit 1.  It would tell me how much electricity was consumed by Unit 1 during the month.  Then I could bill Tenant 1 for that amount and Tenant 2 for the rest.  Does anything like this exist?