I just bought a used VersaClimber CL-108HP (the consumer version with a heart monitor) for $1000. The unit was in excellent condition except for needing a bit of cleaning.
When people say that this unit is BRUTAL, they aren't kidding. The uninitiated get wiped out after about 20 second on this thing, and that's not an exaggeration. The trick is to take SMALL strides to start with. Using one of the program levels in the onboard computer will help you stay within your limits.
The machine is quiet, efficient, and at 4'x3'x7'6", will fit in most apartments. If you haven't been on a VersaClimber, I recommend you at least try one out. You'll be impressed. I've not been on any other piece of equipment that gets my heart rate up as fast as this thing.
Cheers!