Might be a bit late for you but Xiaomen st is the second hand street. full of furniture, tvs, ACs, and junk. It is south of herping west rd, Guting MRT. just look at the map in the MRT station. 

Does anyone know where I can find some second hand furniture for my new apartment? I am new to Taipei, and not sure where to go to get a cheap sofa, bed, and a couple of bookcases. My budget is pretty low, so need second hand.

I have checked out the website here, and there are a few useful posts, but haven't found everything I need.

Where are the second hand shops in Taipei?