Air Conditioning - Moving air handler/furnace

I have a question regarding moving the indoor portion of my central air unit (air handler and furance). How big of a project is this, if I am only having it moved about 4 feet? The gas line will be shortened (no extension of the line), I'm assuming the exhaust through the roof can be elbowed and extended a couple of feet, and most of the duct work runs in the direction of the move (meaning most ducts would not have to be lengthened either). What materials are involved (new freon if the system is drained) and how much time would it take licensed professionals to do it? The move will give us a bunch of usable attic space since we will lose a lot by finishing out a portion of the attic. I have one contractor that said told me over the phone he would charge his hourly labor rate plus materials and another that gave me a flat quote of $1,100. That seemed excessive. Thanks in advance!