Buying used can save good money, but try to do it low risk. If you buy used, confirm that you can return it before buying. I recently bought a used amp that was listed as being in perfect condition. It did look very good, but it had electrical problems. I bought from a positively rated seller on Audiogon, but he refused to accept a return even on a defective item (which was conveyed after I got it and it had problems). I'm currently trying to get the charges reversed on my credit card. Had it worked, it would have been a great deal.
I also bought a pair of used speakers on eBay that work great and were a nice deal.
So, just be smart about it, and used can work out great.