My wife and I will be traveling by train in 4 different countries. If I purchase a "Select Pass", I'll have to add the cost of two reservations for two different journeys for a "double" sleeper. One sleeper journey is in Norway; the other begins in Switzerland and ends in Germany. What is the range of cost for a “double” sleeper reservation and can the reservations be booked on line using a US Credit Card? I've checked DB Bahn but can't get prices on any of the journeys as the train trips are in September—more than 90 days in the future. I checked booking the trains (including sleeper reservations) on Rail Europe, but was frankly taken aback by the bottom line--I thought maybe the Select Pass and "overlaying" the cost of the reservations might result in some savings. But if the savings isn’t much, I’ll proceed with Rail Europe.
Both the DB and www.nsb.no/en have advance-purchase ticket discounts, which you can see by starting out as if to buy a ticket now for an earlier date. Prices are not seasonal; the lowest rates are sold for a few seats and beds, and those rates sell out quickly. If you're concerned about comfort and accommodations on night trains, then also consider flying, which can be pretty affordable; see www.skyscanner.com.
Only consider the Selectpass (from $500 per person) if you have other significant trips to use if for. See also cost comparisons at http://www.ricksteves.com/travel-tips/transportation/trains/cost-maps. Double sleepers average about $80-100 per person in addition to the railpass, without private bath. Rail Europe will show you the price of the sleeper reservations at when you indicate which kind of railpass you have; just pretend to buy one now for an earlier date. The Euraide site mentioned in my last reply also has a pretty good list of night train prices, but not including Norway.
If you have a select pass, which is 1st class, the pass holder supplement for a deluxe double sleeper on the train in Germany (Zürich to Berlin? or any part thereof) is 90€ per adult, and you can book that on the Bahn website. As long as you have a 1st class rail pass, the 1st class, deluxe compartment, with toilet and shower, is the same price as the 2nd class sleeper with only a wash basin.