Though having the appearance of a commemorative medal, this piece in fact appears to be an EXTREMELY RARE trial of the award medal thus created for both Opium Wars. The initial design proposed by Wyon featured the British lion subduing the Chinese dragon, though this seems to have generated some backlash, with the present design supplanting it. While the subsequent award medals (issued in silver and with their corresponding clasps, ribbons, and bars naming the action seen by the recipient) do appear from time to time, bronze versions with no pretensions of being awards are much more difficult to encounter. Rather accordingly, compare to a similar bronze version of the aforementioned original "lion and dragon" design, which sold for a total of just over $50,000 [!] in July 2020.
Estimate: $1000 - $2000