hi
used split forget about it
i have the same problem
the maintenance cost alot because you will need the technician every day and you need 5 units
and to transport the units to your home and bring technician to fix, it cost
and you will need new pipes to connect because you can not use the old pipes all that will cost the sam cost
of the new one
and you have awarrantee for the new unit for the interior
units one year and the external unites 5 year and they can come to you every day you want to fix any problem
specialy at the beginning you will loose the gas from some units and this always happend the company will send
some one to fix or increase the gas and this cost if it is old or used so be careful
buy new unites and be sure from the after sale services of the company , i bought 5 units new and it was cheaper
than the used unit and better ( be carefull )

good luck
nabil