As much as I'd like to buy new all the time, that's not realistic for me. Helmets and blankets aside, I've almost never bought new. In my experience, though, I've been able to pick quality goods every time and it's saved me so much money.
I bought a saddle once, but it was a big disillusion, the photos the owner sent me did not correspond to the product I received at home. The leather was much older than in the photo and there were scratches on the saddle
I am not used to buy used tack. I am a little bit wary about the real state of the product unless it has been used only once but maybe I am wrong! I prefer to pay more and be sure about the quality and good state of the product :)