I'm in a position where I can accommodate a four post lift for working on the cars. These will be Land Rovers at the heaviest. I think I would prefer a four post over a two post that leaves the wheels dangling. I'm thinking second hand to save on cost. The shed that it will go in has single and three phase installed. I don't really know anything about them though. What do I need to look out for? Are there makes to avoid? Are there sources of these that folks know about other than ebay?