AMD Radeon RX Vega graphics cards do very well on the CryptoNight proof-of-work algorithm and miners are using them to mine Monero, Electroneum, Sumokoin, Bytecoin and Karbo. This is because the profitability is better on those coins than Ethereum that uses the Ethash proof-of-work algorithm. It's tough to find an AMD Radeon RX Vega 64 or AMD Radeon RX Vega 56 graphics card due to this. You might get lucky and find some in-stock at Amazon or Newegg, but it is tough. If you switch tactics and look for used AMD Radeon RX Vega 64 cards on eBay you'll quickly find that they are selling for well over $900.