@iro_miya get a vorteilscard for oebb (19EUR for a year, gives you a -50% discount), Wien -> München, from München on a DeutschlandTicket (49EUR), then some ICs on the NL side (doesn’t make sense to buy them much in advance)
worst case scenario: round trip for 100-115EUR, likely less :blobcat3c: altho this is a bit hardcore due to the D-Ticket