Yes bitcoin is designed to be able to buy everything we want. One of which is altcoin, now there are so many exchange that there is internet. So you do not worry to want the altcoin you want to buy. There are many listed exchange, some of which are bittrex, yobit, kraken and also poloniex. You can buy altcoins whenever you want. This is the world of cryptocurrencies, where all free altcoins are used.