I want to measure my own KWH kilowatt hours

One option is to hunt down a (used/refurbished) utility company meter. They aren't too hard to find at reasonable prices because many many utility companies have transitioned over the past several years to meters that can be read remotely rather than by a meter reader. These are quite accurate.

Another interesting option, assuming it is and does what it claims: Neato AC panel meter! At that price, I think it would be worth trying out...very tempting.