It heavily depends on the coin, if it a top 20 coin, there is not much potential in it. So you need ot invest at least 400$ to see some profit.
If you are thinking about smaller coins it could be as small as 50$ and you can see good returns in long term.
You don''t need to invest that much money on an investment. Are you trying to sell your coins or something?
$1 is a lot to invest with.