Okay, I'll play devil's advocate here. I have three used ball-lock kegs, and I sincerely wish I'd bought new. I don't care that they look like they've been run over by a truck. I honestly don't care about aesthetics. My problem is that the price of used kegs (especially ball-lock kegs) is going through the roof, and when you add shipping, we're not talking about 1/2 the price of new anymore (especially when there's a possibility of free shipping with new kegs). To complicate things, two of my kegs arrived with mix-and-match parts (poppets are incorrect, so they don't always seal properly, and there may be other mis-matched/damaged parts, since I'm have trouble getting the liquid dip tubes to seal properly inside the posts, so that I'm often pouring foam). Meanwhile, the third is a Firestone VI (the type that has a plastic gas tube). Add in the price of new parts and additional shipping and the fact that I've got to drill out the Firestone keg to use a metal gas tube, not to mention the frustration involved in working with poorly functioning tools (that is, kegs), and I'd say the cost difference between used and new is negligible and well worth the peace of mind. From now on, I'll only buy new. At least that way, I'll know that the parts will match the keg. And I'll know what the cost will be up front. I, too, am cheap, but I found out a long time ago that sometimes it's less expensive in the long run, as well as less frustrating, to spend more money on a quality tool up front.
'Just my perspective, based on my experience. It looks like other folks have had better luck with their used kegs than I have.