For Nürnberg to Suhl, the SparPreis (advance purchase) fares don't apply, so you'd pay around €61 Return whether you buy the ticket now or on the day.
What you can also do is buy a combination of "Länder-Tickets", which give you unlimited travel on everything below an IC train, as well as local public transport, in the chosen area for a day for a fixed price.
For Bavaria (where Nürnberg is) this is currently €27 for up to five people travelling together, or €19 if you're on your own, and for Thüringia (where Suhl is), it's €26.
HTH,
Southie