Hey Nomad- If i`m not mistaken Optima are AGM and can be found for $130-$170 depending on the model.

http://www.dcbattery.com/optima2.html

Also Nomad, are you going to talk about discharge amps when you talk about inverters because if I`m not mistaken in your discussion of Battery Ratings above you were talking about direct 12v discharge and not the "converted" 120v discharge. I am curious about an appliance that utilizes 120v/5amps what that is through the inverter to the 12v/batteries???