It is really hard to buy a coin which worth 1 satoshi.
I guess the cheapest coin would be priced at 0.1$ or maybe more. Just a rough guess.
have you ever seen the list of altcoins? if you haven't already go here:
https://coinmarketcap.com/all/views/all/ and then click on the price column header to change the sorting of that list with price. check the lowest prices. not only there are 1 satoshi coins but also there are coins worth much less than 1 satoshi.
in case you are wondering how that is possible, these lower than 1 satoshi coins are being traded with coins other than bitcoin. for example with dogecoin so they can have values less than 1 satoshi!