Anyone here know where to locate PROMO CDs and CD SINGLES in GERMANY?

Hi. I think this is kind of a unique question, but hopefully someone can help.

I am looking for some CD Singles and Promo CDs that were issued in Germany, along with some vinyl. Does anyone know of a physical place (not internet) where to get some?

Basically, do any of you Germans who live in Germany know of any music shops where they carry old inventory, which would consist of Singles and Promos? The music I am looking for is in the Hip-Hop / Rap genre, so if you know of some Rock & Oldies stores, that would probably be a waste of time.

Please let me know if anyone knows of some shops, or if you already have some Rap / Hip-Hop items. Thanks.