We bought Protex Pawz at Petco (also available via Amazon) for our Golden Retriever. They work well and he's very tolerant of them. In fact, once he's got them on and steps outside all he wants to do is run like a lunatic.
www.pawzdogboots.com
We turned them inside out and reinforced the bottom with a bit of duct tape (to protect against nail punctures) and then flipped them right-side out to put them on him. It does take two people to put them on, though: one to help hold his paw and the other to spread the mouth of the bootie wide to slip it on.
Had them a week and so far so good. Deep snow no problem and walking on salt covered pavement, no problem.