He's obviously selling it for the gold. It's quite common and any gold buyer would be willing to purchase. The value all depends on how much gold is in the alloy. Could be low or high, you'd need to let a professional determine that. $50 is probably fair.
I'm sure there must be a few grams in this. The second picture shows it goes inside the the plate you can see the loop.
I'll give this thing a little while longer then i'm going to Dissect the gold met it into a nugget.