Best places to buy music in Germany and Poland

[Guttmann]

so, in less than a month ill be away on a holiday to Poland and Germany and im looking for some good places in Warsaw, Krakow and Berlin to buy some music. (especially completing Opeth' disco and maybe buying the new PT. oh and probably some shirts too)
i know one place in berlin, in front of the Europa Center in Kudammstrasse (called Cover i think..).
any other suggestions?

thanks a lot!