Was wondering how I could measure 34 circuits. Sounds like its as simple as buying 3 of these?

Just want to make sure before I start planning the budget its as simple as that!

That would work. Understand that if you want to aggregate the data you would need to upload it to a database like influxDB or Emoncms.

Also, there are methods of combining circuits into one input, so with two you can monitor 28 circuits and if you can combine some that might be enough.