My last several purchases were 2nd hand; 2 compacts(G11,P7100), Gitzo ballhead, D3000...All from an acquaintance. D5000 from e-Bay. 100% satisfaction.
Only from a 2nd Hand photography shop in manchester called Real Camera.
Only when I Can get proof that it is mor stolen.
I love to adapt old second hand gear (Lens etc) for use with modern digital cameras.
Old glass can be very cheap and really good quality.
As long as its in good condition ^_^
I would gladly purchase second hand, if I know the history and it's in great condition. Purchasing from internet without know, would be a no-no. From someone that I know or a company with a good reputation, yes.
I would purchase used equipment if I believed the equipment was in good condition