I realize this is an older thread, but my wife and I are making this trip in June. Looking at the DB website, I can book the bus/ICE combination for €34 each in 2nd class. The all rail service is €63 each in 2nd class. This is the "Standard" fare and no "Savings" fare is shown. Given this difference, I assume the bus is the way to go. Is it possible/likely a cheaper fare would become available later for the all rail service, and if so, should I wait for it ?

I've tried to look at the fares on the www.cd.cz site, but it doesn't want to price the tickets, stating "For the price of a journey outside the territory of the Czech Republic, please contact our Contact Centre or a station ticket counter." Is there another way to find out the prices on a Czech site ?