i've just been to berlin for lollapalooza and stayed a couple extra days to get to know the city! i payed 47€ for two nights in a hostel (and it was really fancy for that amount of money) and the flights weren't really expensive either. so if you're thinking of going, it might be cheaper than you think
also, i'm going to munich, vienna and prague next year and since i'm going alone, i do have a free spot in my car for germany and czech republic