Me and a couple of friends bought Interrail passes for our Summer trip this year. I was trying to make some train reservations at https://reservations.interrail.eu/ , but the process doesn't seem to be transparent at all.

As an example, I selected this options for one of the reservations:

How can I know the prices of each of the accommodation preferences I selected? The page states that the prices are indicative, but I'd like to know how much each alternative would cost me, in order to decide which of them is more suitable to our budget...

Thanks in advance!

EDIT: As I was suggested to use other reservation services, here are the trips that need reservation AFAIK:

• Milan - Venice
• Venice - Vienna (night train)
• Budapest - Zagreb -> I won't use this one to sleep in (only a 2h trip), but it will be a night train, so reservation is required...
• Zagreb - Split (night train)