Gold Rush is one of the three skins released in the Leprechaun's Treasure part of the St. Patrick's Day offer. It could be purchased as part of an item deal in mid March 2017.
Gold Rush could be purchased for $9.99 in a limited time deal that included 16000 coins. It was not available for individual purchase and may not be available for purchase in the future.
Details of this offer may vary depending location, platform or time.
Note: The Leprechaun's Treasure sub-offer was released again for a limited time in mid March 2021. The price and included coins for Gold Rush remained the same for this release.