Hello Michael, Welcome to The Acaeum.

This isn't considered a highly collectible item, so you could expect it to sell for about $20-25 in the condition stated.  With the COA and provenance, perhaps $30-50 if listed properly.  If you list it with a high BIN or Make Offer, it might take a while to sell, though.

Listing on eBay would be easiest, and likely your best venue, but you could also try Facebook groups, such as the following:

RPG Market (Buy and Sell Games)
https://www.facebook.com/groups/rpgmarketgroup

Dungeons & Dragons: Buy, Sell, and Trade
https://www.facebook.com/groups/741551086592501

RPG Auctions
https://www.facebook.com/groups/RPGAuctions

Role Playing Games & Miniatures (Sales & Trades)
https://www.facebook.com/groups/RPGsalestrades

You can also advertise it in the Classifieds on The Acaeum.