Buying used vs. New

Does anyone have reservations about buying used?
I used to swear buy it until recently. I bought a preamp that arrived with a humming problem from the transformer because the delivery company dropped it. Fortunately, I had bought it new and the store was able to replace it. I was just thinking, what if this was used, I would be out of luck in terms of getting it fixed. Also, I bought a used piece of equipment on Audiogon a few years ago that is now giving me trouble. It is out of warranty and was fairly expensive, and now has issues. Now I'm seriously considering buying new, even though my money will only stretch about half as far.