I purchased a model SF-709 from SEC America at: http://www.secamerica.com/
I checked out their web site; and, it looks like this model is still available---I'd recommend the company (Made in USA - Vermont). You'll also need at least one deep cycle 12 volt battery to provide the proverbial electro motive force... I picked up a marine battery at Sam's Club for a reasonable price. Adding additional 12 volt batteries in paralled simply extends your potential running time.
During ice storm power outages my SF-709 inverter keeps my Keystoker Koker running without any problems---until I get my diesel generator cranked up. I've had no problems with the simple electrical controls on the Koker; and, the inverter handles the in-rush current of the convection fan without any problem.
With a direct vent stove, I wouldn't go without a heavy duty power converter for back-up power---carbon monoxide kills...