Jaime Hernandez: The $25 2008-W Proof Gold Buffaloes are the first proof $5 denominations that have ever been offered by the U.S. Mint, with the Gold Buffalo design and also composed of 24 kt pure gold.
These coins were sold as a single coin option or they could also be purchased as a four-piece set.
The four-piece set included a $5, $10, $25 and $50 Uncirculated Gold Buffalo, all produced on special burnished planchets which can be distinguished by the W mint mark.
The coins were released on July 22, 2008.
The U.S. Mint offered the single coins at $619.95 each.
The U.S. Mint offered the four-piece proof set at $2,219.95 each