My wife and I would like to take the night train from Munich to Budapest in late Nov. 2015. A private car or accommodations for two is acceptable. What would be the approx. cost?
By "private car" do you mean you want the whole rail car to yourselves? That's not likely to happen. Accomodations for two would mean a couchette or equivelant. That's a nice experience. Once was enough for me. The three times that we have had an night train experience was two too many. I will say that overnight trains in western and central Europe are more comfortable, by far, that those of eastern Europe. Sleep tight.
It looks like there is only one night train, EN 463, direct from Munich (23:36) to Budapest (9:05), 9½ hours. It has economy (bathroom at the end of the car) sleepers only. Two people in a double sleeper would cost 278 € for both of you, if you purchase the tickets and accommodations at the same time, any time. If you purchase them together (transport and accommodations) in advance from the Bahn they would cost 198 €. Advance purchase tickets would have limited refundability or exchangeability.