We live in a low price market (frugal German/Polish heritage) and there are a number of regular sellers which makes it hard to compete unless you are picking stuff up dirt cheap. I don't even try and use it move stuff I just want gone. I'm very selective about stuff I pick up. I picked up 3 bikes for free recently, stripped parts off the 2 beaters, donated the rest of them, and will make something off the Koga-Miyata after overhauling and replacing consumables.
Your other option is Ebay to widen your market but that brings about more hassles and shipping.
Time of year also makes a difference in prices and demand. You aren't selling squat in Jan unless it's practically free.