Uphold: It is a both wallet and exchange platform, it is centralized and it allows the buying and selling of Dash through US dollars. Uphold uses credit/debit cards and bank transfers as payment methods. Its fee range depends on the fiat currency or cryptocurrency to be exchange.
Bittrex: It is a centralized exchange where Dash can be obtained through US dollars or other cryptocurrencies. Bittrex allows bank transfers a cryptocurrencies deposit as payment methods. Also has a 0.25% fee for all the operations.
Changelly: It is a decentralized exchange whose buying and selling of cryptocurrencies is instantaneous. Also, the platform provides the best offers to the user according to its necessities. Changelly accepts banks transfers in US dollars as payment method and it has a 5% fee per transaction.
Bitfinex: It is platform perfect for trading, it is centralized and it allows the buying and selling of Dash through US dollars. Its fee range varies depending on the cryptocurrency and the transaction amount.