You could take a Eurolines bus directly from Nuremberg to Prague for 39 € (or 3535 € for "Promotional Ticket - can not be changed or refunded!")
The trip takes 4 to 4½ hours, and looks like there are 1-3 daily connections.
I don't know if this is the cheapest public transport option available (probably not), but it's much better than the ICE price, and quite convenient because it's a direct connection.