One of the hoppers I had a bid on (painted and weathered for the Lehigh) went to over 160 bucks...from the same seller from whom I obtained mine. I stopped bidding at 90 bucks.
I’ve noticed that the majority of brass O scale on eBay are either locos, hoppers, or tankers. Relatively few boxcars, stock cars, or reefers.
Another hopper I got on eBay seems to be plastic sheathed in tin, or something like that.