Hi, from 11 June 2023 will DB - Deutsche Bahn increase the cost of a seat reservation.

• 2nd class from 4,50 € to 4,90 € per journey
• 1st class still 5,90 € per journey, but customers with Super Sparpreis and Sparpreis fare will not get the reservation for free anymore. Should be less reserved in 1st class in Germany 
• Family reservation from 9 € to 9,80 € per journey

You can pay less using ÖBB or CD reservation service for 3 EUR/train or 72 CKZ/train

But keep in mind that the price is still for a journey and not per train, so often it cost less than two reservations from ÖBB or CD.

Via Interrail.eu or Eurail.com the cost is 6 EUR + 2 EUR fee per train. Avoid this service for trains with optional reservation in middle Europe and German speaking countries.