Welcome to APUG, I spent a lot of time in BR a few years back.
Completed prices on ebay would be the best place to start.
Aside from that one of these was in the recent PHSNE (Photographic Historical Society of New England) auction.
It collected no bids, and there was no minimum bid amount for it.
My recommendation would be to consider keeping the lens to market somewhere like APUG, or perhaps ebay, and sell the rest of the enlarger to someone doing Steampunk.