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.
This gold coin in uncirculated condition is worth $90.00.
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.
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.