Cheapest way to do just power monitoring

Hi all,

I started a thread about a "whole hog" type system, I'm also interested in the cheapest solution for just power monitoring, I didn't want to distract that thread. Is it possible to use one R.Pi along with an optical utility sensor to both count the pulses and send the data up to EmonCMS using the R.Pi WiFi? Or do you need two units, one to count the pulses and one to send up to the internet?

If the above can be done with one Pi, and if you wanted to extend the system later to collect temperature data, would you need to add an EmonBase and an EmonTX before you could add temperature sensors?

Thanks for any thoughts or advice :)