Did you know that your blender can grind coffee beans also.. (providing you own a blender) Just an option that is also available if all else isn't.
Related: Where can I buy a small coffee grinder in Warsaw?
Which store in Warsaw might have a coffee grinder or something to grind coffee. It must be small because I want to bring it in my luggage and it can be a manual grinder, I don't need to grind very fast.
Saturn (in Arkadia or Zloty Tarasy). Or any large grocery store like tesco, real or auchan has them. I saw a manual coffee mill at the Merkury (small department store) in Żoliborz on Słowackiego Street.