GBM,

In looking around the web I came across the following sites, maybe this
will give you some additional pointers. As to prices, I think the off
the shelf device you are interested in will run you at least $200
dollars, if not more.

http://www.wholesalesolar.com/produc...etric2020.html
http://www.pkys.com/AmpHour.htm
http://www.solardepot.com/dpc_system_monitors.htm

Alternatively, a cheap inductance meter is about $50 and a data logger
can be built for under $100, but you'd need to be comfortable with
soldering, wiring, etc.

http://www.onsetcomp.com/Newsletters...ome_power.html
http://www.hobbyengineering.com/H1251.html

Hope this helps.

Cheers,

Robb