Most dealers will pay you around spot price minus 2% for metal.
The dealers I work with pay full spot or higher depending on demand and condition.
Darwin is a hot and humid place, do your coins have any toning?
To most dealers it doesn't matter. To most private buyers it does matter.
50c rounds... spot+$1 is a fair price to pay per coin, though I have seen them selling for spot+$20, which is quite high for a mass produced, circulated coin. It shouldn't be priced like 999 bullion but some people like to price gouge.
2012 Perth Mint lunar dragons... Jaggards is selling them for spot+95%, selling to a private buyer, spot+50% is reasonable.
Predecimals... will appeal to older or budget stackers, pricing seems to be based on 500g or 1kg weights. I don't like them due to the odd weights, lower purity, spot price is fair.
999 troy ounces usually sells easier than pre decimal stuff,
