For a tripod, go used.
I've recently purchased one off of eBay and I'm very happy with it, even though it is rather heavy. (Heavy usually means more stable.) Make sure the seller has a good rating and offers returns at least if it does not measure up to the description or is damaged in shipping. Read the item description carefully and look for details about the item condition. Ask them questions if you have any, and never get rushed or caught up in an eBay auction. If you miss this one, another will likely come along in the future.
And most importantly, know the value of the item you are going to bid on, to ensure that you don't pay more than you would if you purchased it retail used or new.
WM