I have ordered four kegs from Kegglebrewing.com since they sell them cheaper for HBT members, and they were covered with stickers and still had soda residue inside them, but otherwise fine. Unfortunately, one was a Firestone VI keg that I still have problems with even after buying $15 worth of replacement parts. Other than that, the kegs have worked very well, and I am happy with my purchase. Unfortunately, the price has gone up quite a bit, so it's not as great a deal as these used to be, and their shipping is pricier than most.
I have also purchased a keg from BMW, which was in great condition, and that's probably where I'll go back to when I need more kegs. The price is reasonable and they stand behind their product.