Today, we’ll learn how to buy an NFT on an open marketplace using a self-custody wallet. Ethereum, Polygon, Solana, and Tezos are the main smart contract blockchains that have active marketplaces for NFTs. And to buy NFTs on these blockchains, you'll need some of the blockchain's native currency to pay for the NFT and the associated fees. Ethereum, where most of the prominent collections are found, requires ETH.