What an amazing medal. They come in bronze, silver, and gold, in commemoration of the coronation of William IV and his wife Adelaide. Any of them would be a fine addition to any collection.
Value, of course, varies with metallic composition and state of preservation. Here are approximate catalog values:
worn: $20 US dollars approximate catalog value
average circulated: $40
well preserved: $90
fully uncirculated: $300
worn: $35 US dollars approximate catalog value
average circulated: $65
well preserved: $150
fully uncirculated: $600
worn: $1000 US dollars approximate catalog value
average circulated: $1200
well preserved: $1600
fully uncirculated: $2500
The gold example in our main picture comes from Stack's Bowers. Stack's medal sold for $1900 US dollars in a 2011 auction. Another price point is set by the bronze medal which is currently on sale at M&H Coins in London. M&H has it listed for 175 GBP, or about $290 USD. If you had a bronze medal and wanted to sell it to a reputable dealer like M&H, figure the offer to buy your medal would be between $100 and $150. The markup is necessary to keep the dealership solvent.
CoinQuest thanks Stack's Bowers and M&H Coins for use of their great coin photos.