There's one that I know of in Warsaw near the Central Railway Station, the address is Chmielna 98 and the name of the store is Swiat Gier (or SwiatGier. c o m, cuz they're selling mainly via the web I guess). I haven't been there for a while, but I hope the place still exists :)
Thanks, the website still works, but I am in Gdansk, so Warsaw is a bit far for me =P