You can usually find stuff on craigslist or ebay. My advise is to buy new. You're putting your life on the line and there's no way of knowing the history of used gear. If you're determined to buy used buy spikes or a saddle. No carabiners and absolutely no used climbing line. I bought some used kernmantle to try it. Didn't like it so we used it for light rigging and we even pulled a few trees over with it. That stuff still looked great after a few years of abuse. Sometimes you just can't tell. Safety is way cheaper than injuries.
Good luck,
Phil