It used to be that if I wanted furniture, I'd go to the second hand store, and look for some used furniture that fitted my purpose. If I couldn't find something that worked, then I'd look online, and then failing that, I'd buy it new.
I found some real gems at the second hand store. A desk I bought is going strong 5 years later (I gave it to a friend).
Now I don't even bother, I just go straight to Ikea. It's so cheap that there's no point in looking at second hand.