Would this be worth trying to sell on Ebay or Amazon?

A search for "VINTAGE BOX FANS" on eBay shows 113 sold over the past 90 days. I wasn't able to find FrostPaire, and most that sold were in better condition then the one you have. I usually list items for 30 days and see if they sell. If there's a decent number of views/watchers then I might relist it for another 30 days. Adjusting the price at that point might help it sell. After 60 days I usually scrap it, or look for another avenue to sell it. I've been fortunate to sell just about every item I've listed on ebay, even if there were no past sales or very few. My guess is it would probably sell if it was restored and cleaned up, but might be one of those items you have to sit on for awhile.