Like 10 foot. But a dual post would take up too much space, require drilling into the slab, require running a 240V line, and require spending a heck of a lot more than $900. Not gonna happen.
For the stuff I do, the Quick Jack would be perfect.
Check out the MaxJax, you do have to drill and insert the mount points but the posts are not permanent it takes about 10 minutes to set up or take down. They have wheels so you can store it all in a corner when not in use. The 10 foot ceiling is good, the problem however is usually the door opener that hangs down a couple of feet. If you could manage it the 4 foot lift height would be pretty nice.
Paul - 1972 Spider - (2)1991 164S's - 1983 308 - 2001 Discovery - 1997 F350