They do a dinner meal for 200 Dirham which is a 3 course meal in the evenings.
The average price is around 150 Dirham for a main meal. That is the average price around Marrakech.
Drinks - alcohol is a little more expensive but that is the same everywhere too. Around 120 Dirham for a glass of wine or 70 Dirham for a beer. Soft drinks are 60 - 80 Dirham.
Get an answer from Palais Jena & Spa staff and past guests.