In Warsaw you could try Hotel Mazowiecki. I typed in random dates in April onto their website and kept getting a message that no rooms were available, but on booking.com found a few singles (I believe with bathrooms in the hall) for 49E. It's about a 20 minute walk to the central train station and two blocks from Nowy Swiat, which turns into Krakowskie Przedmiescie, the main drag leading you to Warsaw's historic center. Breakfast should be included and the staff spoke enough English and were incredibly helpful. The only issue to be aware of is that there's a nightclub (or two?) on the same street. On one trip I remember it being loud at night, so they moved me to a back room. But for money and location, I think it's a great deal.
In Krakow I've always stayed at BB La Fontaine; their website lists rooms for 42E/night, with bathroom. The main building is right on the corner of the main square. There's an annex a block or two off the square that I've stayed in once before. Breakfast included in their cellar restaurant; lots of stairs, but friendly staff.
Hope these help!