I think that you need to think hard about whether you genuinely need to monitor all your circuits all the time. What are you planning to do with the data? If you really want to evaluate your home's energy usage on a circuit by circuit basis, this can be done serially over a few weeks, which is much more cost-effective than buying the hardware to monitor every circuit 24/7 going forward. In most situations, too, this sort of energy surveying is best done using a Kill-A-Watt or equivalent to look at the energy draw of specific devices or sets of devices (e.g. a home theater setup). Once you have established where your issues are, you are likely to find a relatively small number of circuits that need monitoring over the longer term.
