Whenever I travel, I offer my flat to whoever needs a cheap stay central in Nørrebro.
That flat is neat and in a very good shape. It's fully equipped and has two rooms - bed room and living room with a big couch that does fine as a bed as weel - plus a fully equipped kitchen, a large bathroom and a long hall. All in all 67 m2.
The flat can host up to three persons depending on your willingness to share the bed (130 cm wide) and use the couch (1.85 m long). It's perfect for couples, but it'll do fine for a couple of friends as well and it's cheap enough for singles.
The building has great laundry facilities and it's included in the rent, if you stay for more than 10 days.
The flat is situated a five minute walk from Sankt Hans Torv and Elmegade. I share the backyard with a very nice and popular bar/restaurent 'Wascator', and the neighbourhood is really great.
The whole of Nørrebro and Østerbro is withing walking distance and the rest of the city is easy to access with a bike. Otherwise take a bus one minute away from the flat.