Any coin dealer would most likely buy the coin from you. Alternatively, you could try eBay.
An Uncirculated $2.50 gold US coin is worth $425 in MS-60 uncirculated.
An Australian 1984 Two Hundred Dollar gold coin (Koala), uncirculated and in absolute mint condition could fetch up to $420 AUD. There were 49,200 minted. An Australian 1984 Two Hundred Dollar gold coin (Proof)(Koala), uncirculated and in absolute mint condition could fetch up to $440 AUD. There were 12,584 minted. Any valuation presumes that the coin is in the original packaging and remains in mint condition. A reputable coin dealer will be able to give a more accurate valuation.
A 1912 $5 gold coin is worth $600 in MS-60 Uncirculated condition.
A 2006-W American Eagle bullion gold coin is worth in an uncirculated state: $90.00; should this coin be in a proof state, its value is: $125.
August 18, 2009 The Jamestown 400th Anniversary Commemorative Coin was issued in silve and in gold. In silver the uncirculated value is about $35. In gold the uncirculated value is about $230.
The 22 carat gold koala series of coins was last issued in 1986.
An Australian 1987 Two Hundred Dollar (gold) coin (First Fleet Departure), uncirculated and in absolute mint condition could fetch up to $420 AUD. There were 20,800 minted. An Australian 1987 Two Hundred Dollar (gold) coin (First Fleet Departure)(Proof), uncirculated and in absolute mint condition could fetch up to $440 AUD. There were 20,000 minted. A reputable coin dealer will be able to give a more accurate valuation. Composition is 91.67% gold and 8.33% copper. Edge reeded. Weight 10 grams. Diameter is 24 mm.
This gold coin in uncirculated condition is worth $90.00.
about $300.
What country? What year?
About $35,000
If you mean an 1853 $1 gold coin value can be $125.00 to $270.00 for a circulated coin. And more than $300.00 for uncirculated coins.