As always, YMMV!
Saw this whole house fan at the Lowes in Torrance, CA (Western Ave) for $87.17, supposed regular price of $349.
Yes, summer is over but this whole house fan may help next summer, to cool down your hot attic in the evening so you don’t need to run your AC as much.
If you’re handy you can probably install it yourself depending on your skill/knowledge level. If not, hire someone.
There were two at this store, but we bought one. Good luck!
https://www.lowes.com/pd/Air-Vent…an/3563350