I found this site for duct/booster fans and ordered an 8" for my stove for the helping the existing blower on the stove. They also have the dimmers for motors.
I Ordered it off their ebay store and had it in a few days! (Saved a couple bucks!)
Also, these will go to 250-260 Degrees! Most of this type are Plastic blades, these are the only ones I could find with METAL blades and at a very good price!!
This link is broken, either the page no longer exists or there is some other issue like a typo.
(FYI - I am NOT affiliated at all with this site.)