I have an Alaska Kast Console II. I had to replace the power vent in Jan 2004. My dealer/coal supplier sold me a Field Controls SWG-4HDs Stainless Steel power vent, which has a 4" inlet, for $375. I just did a quick search and found a website (patriot-supply.com) which has the same vent for $277.58 + $12.84 s/h to western NY state.
It works great but I did have one problem... the vent has an airflow adjustment damper built in. Probably during a time when the stove wasn't being used, the locking screw on the damper rusted due to moisture in the pipe. This now prevents me from making adjustments to the damper, but this really isn't a problem since once you set it, you don't need to make any more adjustments.
You can go to Field Controls website for more info on this and other vents which migth be what you need. This page shows the different models with specs:
They also have their product manuals online at this address: