Gold Bar Sellers 0.5 G Gold St. Gaudens 20$ Bar/scrap/bullion...does This Coin Has Any Value?

0.5 g gold st. gaudens 20$ bar/scrap/bullion...does this coin has any value? - gold bar sellers

They say they are $ 20 for use as a value of $ 20? There are about 500 coins sold on eBay to a single vendor ... Type curious to know where he gets his by ... I could not find anywhere on the Internet, except ebay ... I Might Be Wrong ... someone willing to give an idea?