Hi Charde,
Like your style! I too am in Luzern and I pretty much furnished my whole flat with stuff that was either free or dirt cheap... hmm, maybe, it's an Aussie thing... (and that was BEFORE I discovered the English-Forum!)
The free sofa-bed was indeed fire-engine red, but I think it has lots of character

Ok...
1) Check out
www.gratis-inserate.ch
A bit like the 'Trading-Post'.. but also contains quite a few free items. Great for furniture
2)
www.ricardo.ch- a bit like ebay, can also find some bargains.
3) "Brockenhaeuser" (=Op Shops).. great for bits and pieces, kitchen utensils, pillows, bed linen, lamps, pots and pans etc. NOT always great for larger furniture like beds, tables, so be careful (often not much difference to buy new)
There are 2 main ones in Luzern. 1) Luzerner Brockenhaus, Klosterstrasse 14; and 2) Caritas Laden, Bleicherstrasse 10. Also a smaller Salvation Army (Heilsarmee) place in Habsburgerstrasse.
4) The flea-markets down by the Reuss run from June-October.
Can you tell I moved here as a student?

Best of luck with your move. Feel free to get in touch if you need help with anything, by the way.
Cheers!