I did a search on belt buckles on this site and found lots of interesting information.
First, there's quite a spectrum of TSR belt buckles that were made, and the Lizardman version was apparently made first! Here's Frank Mentzer's collection:
Cyclopeatron: Mentzer's TSR Belt Buckle CollectionSecond, the Lizardman version was not as good a quality as the following belt buckles. Any auction would need to show that yours is not broken. Here's the history of the belt buckles and some info on their rarity.
http://thecollectorstrove.com/arc-wdh-20090802/One sold back in 2016 for at least $410. And since collectibles like this have been rising in price, I am confident you could get at least $500.00 for it.
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