If you want second hand, try Gumtree Polska or Allegro.pl. Also the place in the entrance of major supermarkets where people leave cards selling second hand items. If Volksbank are part of the Visa or Maestro networks you will find an ATM that works.
you'd probably need someone speaking polish but tablica.pl is a way to go for second hand LCD monitors, some would deliver also under "firmowe' you'd see companies not individuals offers - they couold deliver (I think). Ohter then that allegro.pl