in capital cities an average room will cost 20-25 euros. You can get them cheaper if you book far in advance sometimes and sometime you will pay more. It just dpeends on the hostel. I stayed in a hostel in Berlin that charged us 14 euros a night. However, travelers coming in that day were being charged 25 euros a night. Not all hsotels give major discounts like that but you can assume you will pay 20-25 euros a night for hostels in major cities in western Europe.
"Sundace, I can't help you now."